diff --git a/requirements.txt b/requirements.txt
index 941877d2b3..b2e32385dd 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -31,8 +31,6 @@ isort==5.11.4
 mypy==0.982
 types-certifi==2021.10.8.2
 pytest==7.2.0
-pytest-asyncio==0.20.3
-pytest-trio==0.7.0
 trio==0.21.0
 trio-typing==0.7.0
 trustme==0.9.0
diff --git a/setup.cfg b/setup.cfg
index 8077a27542..d9b822c1e0 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -18,7 +18,7 @@ combine_as_imports = True
 addopts = -rxXs
 filterwarnings =
   error
-asyncio_mode = strict
+  ignore: You seem to already have a custom sys.excepthook handler installed. I'll skip installing Trio's custom handler, but this means MultiErrors will not show full tracebacks.:RuntimeWarning
 markers =
   copied_from(source, changes=None): mark test as copied from somewhere else, along with a description of changes made to accodomate e.g. our test setup
   network: marks tests which require network connection. Used in 3rd-party build environments that have network disabled.
diff --git a/tests/client/test_async_client.py b/tests/client/test_async_client.py
index cd34022e91..61ad5101dd 100644
--- a/tests/client/test_async_client.py
+++ b/tests/client/test_async_client.py
@@ -6,7 +6,7 @@
 import httpx
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_get(server):
     url = server.url
     async with httpx.AsyncClient(http2=True) as client:
@@ -27,14 +27,14 @@ async def test_get(server):
         pytest.param("http://", id="no-host"),
     ],
 )
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_get_invalid_url(server, url):
     async with httpx.AsyncClient() as client:
         with pytest.raises((httpx.UnsupportedProtocol, httpx.LocalProtocolError)):
             await client.get(url)
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_build_request(server):
     url = server.url.copy_with(path="/echo_headers")
     headers = {"Custom-header": "value"}
@@ -49,7 +49,7 @@ async def test_build_request(server):
     assert response.json()["Custom-header"] == "value"
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_post(server):
     url = server.url
     async with httpx.AsyncClient() as client:
@@ -57,7 +57,7 @@ async def test_post(server):
     assert response.status_code == 200
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_post_json(server):
     url = server.url
     async with httpx.AsyncClient() as client:
@@ -65,7 +65,7 @@ async def test_post_json(server):
     assert response.status_code == 200
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_stream_response(server):
     async with httpx.AsyncClient() as client:
         async with client.stream("GET", server.url) as response:
@@ -76,7 +76,7 @@ async def test_stream_response(server):
     assert response.content == b"Hello, world!"
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_access_content_stream_response(server):
     async with httpx.AsyncClient() as client:
         async with client.stream("GET", server.url) as response:
@@ -87,7 +87,7 @@ async def test_access_content_stream_response(server):
         response.content
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_stream_request(server):
     async def hello_world() -> typing.AsyncIterator[bytes]:
         yield b"Hello, "
@@ -98,7 +98,7 @@ async def hello_world() -> typing.AsyncIterator[bytes]:
     assert response.status_code == 200
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_cannot_stream_sync_request(server):
     def hello_world() -> typing.Iterator[bytes]:  # pragma: no cover
         yield b"Hello, "
@@ -109,7 +109,7 @@ def hello_world() -> typing.Iterator[bytes]:  # pragma: no cover
             await client.post(server.url, content=hello_world())
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_raise_for_status(server):
     async with httpx.AsyncClient() as client:
         for status_code in (200, 400, 404, 500, 505):
@@ -125,7 +125,7 @@ async def test_raise_for_status(server):
                 assert response.raise_for_status() is None  # type: ignore
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_options(server):
     async with httpx.AsyncClient() as client:
         response = await client.options(server.url)
@@ -133,7 +133,7 @@ async def test_options(server):
     assert response.text == "Hello, world!"
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_head(server):
     async with httpx.AsyncClient() as client:
         response = await client.head(server.url)
@@ -141,21 +141,21 @@ async def test_head(server):
     assert response.text == ""
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_put(server):
     async with httpx.AsyncClient() as client:
         response = await client.put(server.url, content=b"Hello, world!")
     assert response.status_code == 200
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_patch(server):
     async with httpx.AsyncClient() as client:
         response = await client.patch(server.url, content=b"Hello, world!")
     assert response.status_code == 200
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_delete(server):
     async with httpx.AsyncClient() as client:
         response = await client.delete(server.url)
@@ -163,7 +163,7 @@ async def test_delete(server):
     assert response.text == "Hello, world!"
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_100_continue(server):
     headers = {"Expect": "100-continue"}
     content = b"Echo request body"
@@ -177,7 +177,7 @@ async def test_100_continue(server):
     assert response.content == content
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_context_managed_transport():
     class Transport(httpx.AsyncBaseTransport):
         def __init__(self) -> None:
@@ -209,7 +209,7 @@ async def __aexit__(self, *args):
     ]
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_context_managed_transport_and_mount():
     class Transport(httpx.AsyncBaseTransport):
         def __init__(self, name: str):
@@ -254,7 +254,7 @@ def hello_world(request):
     return httpx.Response(200, text="Hello, world!")
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_client_closed_state_using_implicit_open():
     client = httpx.AsyncClient(transport=httpx.MockTransport(hello_world))
 
@@ -275,7 +275,7 @@ async def test_client_closed_state_using_implicit_open():
             pass  # pragma: no cover
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_client_closed_state_using_with_block():
     async with httpx.AsyncClient(transport=httpx.MockTransport(hello_world)) as client:
         assert not client.is_closed
@@ -296,7 +296,7 @@ def mounted(request: httpx.Request) -> httpx.Response:
     return httpx.Response(200, json=data)
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_mounted_transport():
     transport = httpx.MockTransport(unmounted)
     mounts = {"custom://": httpx.MockTransport(mounted)}
@@ -311,7 +311,7 @@ async def test_mounted_transport():
         assert response.json() == {"app": "mounted"}
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_async_mock_transport():
     async def hello_world(request):
         return httpx.Response(200, text="Hello, world!")
@@ -324,7 +324,7 @@ async def hello_world(request):
         assert response.text == "Hello, world!"
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_cancellation_during_stream():
     """
     If any BaseException is raised during streaming the response, then the
@@ -364,7 +364,7 @@ async def aclose(self) -> None:
         assert stream_was_closed
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_server_extensions(server):
     url = server.url
     async with httpx.AsyncClient(http2=True) as client:
diff --git a/tests/client/test_auth.py b/tests/client/test_auth.py
index e889d8ef48..cce3495517 100644
--- a/tests/client/test_auth.py
+++ b/tests/client/test_auth.py
@@ -3,13 +3,13 @@
 
 Unit tests for auth classes also exist in tests/test_auth.py
 """
-import asyncio
 import hashlib
 import os
 import threading
 import typing
 from urllib.request import parse_keqv_list
 
+import anyio
 import pytest
 
 import httpx
@@ -135,7 +135,7 @@ class SyncOrAsyncAuth(httpx.Auth):
 
     def __init__(self) -> None:
         self._lock = threading.Lock()
-        self._async_lock = asyncio.Lock()
+        self._async_lock = anyio.Lock()
 
     def sync_auth_flow(
         self, request: httpx.Request
@@ -152,7 +152,7 @@ async def async_auth_flow(
         yield request
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_basic_auth() -> None:
     url = "https://example.org/"
     auth = ("user", "password123")
@@ -165,7 +165,7 @@ async def test_basic_auth() -> None:
     assert response.json() == {"auth": "Basic dXNlcjpwYXNzd29yZDEyMw=="}
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_basic_auth_with_stream() -> None:
     """
     See: https://github.com/encode/httpx/pull/1312
@@ -184,7 +184,7 @@ async def test_basic_auth_with_stream() -> None:
     assert response.json() == {"auth": "Basic dXNlcjpwYXNzd29yZDEyMw=="}
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_basic_auth_in_url() -> None:
     url = "https://user:password123@example.org/"
     app = App()
@@ -196,7 +196,7 @@ async def test_basic_auth_in_url() -> None:
     assert response.json() == {"auth": "Basic dXNlcjpwYXNzd29yZDEyMw=="}
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_basic_auth_on_session() -> None:
     url = "https://example.org/"
     auth = ("user", "password123")
@@ -211,7 +211,7 @@ async def test_basic_auth_on_session() -> None:
     assert response.json() == {"auth": "Basic dXNlcjpwYXNzd29yZDEyMw=="}
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_custom_auth() -> None:
     url = "https://example.org/"
     app = App()
@@ -227,7 +227,7 @@ def auth(request: httpx.Request) -> httpx.Request:
     assert response.json() == {"auth": "Token 123"}
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_netrc_auth() -> None:
     os.environ["NETRC"] = str(FIXTURES_DIR / ".netrc")
     url = "http://netrcexample.org"
@@ -242,7 +242,7 @@ async def test_netrc_auth() -> None:
     }
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_auth_header_has_priority_over_netrc() -> None:
     os.environ["NETRC"] = str(FIXTURES_DIR / ".netrc")
     url = "http://netrcexample.org"
@@ -255,7 +255,7 @@ async def test_auth_header_has_priority_over_netrc() -> None:
     assert response.json() == {"auth": "Override"}
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_trust_env_auth() -> None:
     os.environ["NETRC"] = str(FIXTURES_DIR / ".netrc")
     url = "http://netrcexample.org"
@@ -280,7 +280,7 @@ async def test_trust_env_auth() -> None:
     }
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_auth_disable_per_request() -> None:
     url = "https://example.org/"
     auth = ("user", "password123")
@@ -302,7 +302,7 @@ def test_auth_hidden_url() -> None:
     assert expected == repr(httpx.URL(url))
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_auth_hidden_header() -> None:
     url = "https://example.org/"
     auth = ("example-username", "example-password")
@@ -314,7 +314,7 @@ async def test_auth_hidden_header() -> None:
     assert "'authorization': '[secure]'" in str(response.request.headers)
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_auth_property() -> None:
     app = App()
 
@@ -330,7 +330,7 @@ async def test_auth_property() -> None:
         assert response.json() == {"auth": "Basic dXNlcjpwYXNzd29yZDEyMw=="}
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_auth_invalid_type() -> None:
     app = App()
 
@@ -348,7 +348,7 @@ async def test_auth_invalid_type() -> None:
             client.auth = "not a tuple, not a callable"  # type: ignore
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_digest_auth_returns_no_auth_if_no_digest_header_in_response() -> None:
     url = "https://example.org/"
     auth = httpx.DigestAuth(username="user", password="password123")
@@ -376,7 +376,7 @@ def test_digest_auth_returns_no_auth_if_alternate_auth_scheme() -> None:
     assert len(response.history) == 0
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_digest_auth_200_response_including_digest_auth_header() -> None:
     url = "https://example.org/"
     auth = httpx.DigestAuth(username="user", password="password123")
@@ -391,7 +391,7 @@ async def test_digest_auth_200_response_including_digest_auth_header() -> None:
     assert len(response.history) == 0
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_digest_auth_401_response_without_digest_auth_header() -> None:
     url = "https://example.org/"
     auth = httpx.DigestAuth(username="user", password="password123")
@@ -418,7 +418,7 @@ async def test_digest_auth_401_response_without_digest_auth_header() -> None:
         ("SHA-512-SESS", 64, 128),
     ],
 )
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_digest_auth(
     algorithm: str, expected_hash_length: int, expected_response_length: int
 ) -> None:
@@ -451,7 +451,7 @@ async def test_digest_auth(
     assert len(digest_data["cnonce"]) == 16 + 2
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_digest_auth_no_specified_qop() -> None:
     url = "https://example.org/"
     auth = httpx.DigestAuth(username="user", password="password123")
@@ -483,7 +483,7 @@ async def test_digest_auth_no_specified_qop() -> None:
 
 
 @pytest.mark.parametrize("qop", ("auth, auth-int", "auth,auth-int", "unknown,auth"))
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_digest_auth_qop_including_spaces_and_auth_returns_auth(qop: str) -> None:
     url = "https://example.org/"
     auth = httpx.DigestAuth(username="user", password="password123")
@@ -496,7 +496,7 @@ async def test_digest_auth_qop_including_spaces_and_auth_returns_auth(qop: str)
     assert len(response.history) == 1
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_digest_auth_qop_auth_int_not_implemented() -> None:
     url = "https://example.org/"
     auth = httpx.DigestAuth(username="user", password="password123")
@@ -507,7 +507,7 @@ async def test_digest_auth_qop_auth_int_not_implemented() -> None:
             await client.get(url, auth=auth)
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_digest_auth_qop_must_be_auth_or_auth_int() -> None:
     url = "https://example.org/"
     auth = httpx.DigestAuth(username="user", password="password123")
@@ -518,7 +518,7 @@ async def test_digest_auth_qop_must_be_auth_or_auth_int() -> None:
             await client.get(url, auth=auth)
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_digest_auth_incorrect_credentials() -> None:
     url = "https://example.org/"
     auth = httpx.DigestAuth(username="user", password="password123")
@@ -531,7 +531,7 @@ async def test_digest_auth_incorrect_credentials() -> None:
     assert len(response.history) == 1
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_digest_auth_reuses_challenge() -> None:
     url = "https://example.org/"
     auth = httpx.DigestAuth(username="user", password="password123")
@@ -548,7 +548,7 @@ async def test_digest_auth_reuses_challenge() -> None:
         assert len(response_2.history) == 0
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_digest_auth_resets_nonce_count_after_401() -> None:
     url = "https://example.org/"
     auth = httpx.DigestAuth(username="user", password="password123")
@@ -594,7 +594,7 @@ async def test_digest_auth_resets_nonce_count_after_401() -> None:
         'Digest realm="httpx@example.org", qop="auth,au',  # malformed fields list
     ],
 )
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_async_digest_auth_raises_protocol_error_on_malformed_header(
     auth_header: str,
 ) -> None:
@@ -626,7 +626,7 @@ def test_sync_digest_auth_raises_protocol_error_on_malformed_header(
             client.get(url, auth=auth)
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_async_auth_history() -> None:
     """
     Test that intermediate requests sent as part of an authentication flow
@@ -686,7 +686,7 @@ async def handle_async_request(self, request: httpx.Request) -> httpx.Response:
         return self.handler(request)
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_digest_auth_unavailable_streaming_body():
     url = "https://example.org/"
     auth = httpx.DigestAuth(username="user", password="password123")
@@ -700,7 +700,7 @@ async def streaming_body() -> typing.AsyncIterator[bytes]:
             await client.post(url, content=streaming_body(), auth=auth)
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_async_auth_reads_response_body() -> None:
     """
     Test that we can read the response body in an auth flow if `requires_response_body`
@@ -733,7 +733,7 @@ def test_sync_auth_reads_response_body() -> None:
     assert response.json() == {"auth": '{"auth": "xyz"}'}
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_async_auth() -> None:
     """
     Test that we can use an auth implementation specific to the async case, to
diff --git a/tests/client/test_event_hooks.py b/tests/client/test_event_hooks.py
index 7c7ce55d48..6604dd31a3 100644
--- a/tests/client/test_event_hooks.py
+++ b/tests/client/test_event_hooks.py
@@ -63,7 +63,7 @@ def raise_on_4xx_5xx(response):
             assert exc.response.is_closed
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_async_event_hooks():
     events = []
 
@@ -99,7 +99,7 @@ async def on_response(response):
     ]
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_async_event_hooks_raising_exception():
     async def raise_on_4xx_5xx(response):
         response.raise_for_status()
@@ -171,7 +171,7 @@ def on_response(response):
     ]
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_async_event_hooks_with_redirect():
     """
     A redirect request should trigger additional 'request' and 'response' event hooks.
diff --git a/tests/client/test_proxies.py b/tests/client/test_proxies.py
index 98dfafab26..3070022fa1 100644
--- a/tests/client/test_proxies.py
+++ b/tests/client/test_proxies.py
@@ -132,7 +132,7 @@ def test_transport_for_request(url, proxies, expected):
         assert transport._pool._proxy_url == url_to_origin(expected)
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 @pytest.mark.network
 async def test_async_proxy_close():
     try:
diff --git a/tests/client/test_redirects.py b/tests/client/test_redirects.py
index 726572f918..b83e667879 100644
--- a/tests/client/test_redirects.py
+++ b/tests/client/test_redirects.py
@@ -151,7 +151,7 @@ def test_next_request():
     assert response.next_request is None
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_async_next_request():
     async with httpx.AsyncClient(transport=httpx.MockTransport(redirects)) as client:
         request = client.build_request("POST", "https://example.org/redirect_303")
@@ -240,7 +240,7 @@ def test_multiple_redirects():
     assert len(response.history[1].history) == 1
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_async_too_many_redirects():
     async with httpx.AsyncClient(transport=httpx.MockTransport(redirects)) as client:
         with pytest.raises(httpx.TooManyRedirects):
@@ -438,7 +438,7 @@ def test_redirect_custom_scheme():
     assert str(e.value) == "Scheme 'market' not supported."
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_async_invalid_redirect():
     async with httpx.AsyncClient(transport=httpx.MockTransport(redirects)) as client:
         with pytest.raises(httpx.RemoteProtocolError):
diff --git a/tests/conftest.py b/tests/conftest.py
index 1cf08af230..4479b2b084 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -34,30 +34,6 @@
 }
 
 
-@pytest.fixture(
-    params=[
-        pytest.param("asyncio", marks=pytest.mark.asyncio),
-        pytest.param("trio", marks=pytest.mark.trio),
-    ]
-)
-def async_environment(request: typing.Any) -> str:
-    """
-    Mark a test function to be run on both asyncio and trio.
-
-    Equivalent to having a pair of tests, each respectively marked with
-    '@pytest.mark.asyncio' and '@pytest.mark.trio'.
-
-    Intended usage:
-
-    ```
-    @pytest.mark.usefixtures("async_environment")
-    async def my_async_test():
-        ...
-    ```
-    """
-    return typing.cast(str, request.param)
-
-
 @pytest.fixture(scope="function", autouse=True)
 def clean_environ():
     """Keeps os.environ clean for every test without having to mock os.environ"""
diff --git a/tests/models/test_requests.py b/tests/models/test_requests.py
index 85594942b3..690b0e17df 100644
--- a/tests/models/test_requests.py
+++ b/tests/models/test_requests.py
@@ -86,7 +86,7 @@ def test_read_and_stream_data():
     assert content == request.content
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_aread_and_stream_data():
     # Ensure a request may still be streamed if it has been read.
     # Needed for cases such as authentication classes that read the request body.
@@ -192,7 +192,7 @@ def test_request_picklable():
     }
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_request_async_streaming_content_picklable():
     async def streaming_body(data: bytes) -> typing.AsyncIterator[bytes]:
         yield data
diff --git a/tests/models/test_responses.py b/tests/models/test_responses.py
index acb9bd4514..cbd71e8b52 100644
--- a/tests/models/test_responses.py
+++ b/tests/models/test_responses.py
@@ -331,7 +331,7 @@ def test_empty_read():
     assert response.is_closed
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_aread():
     response = httpx.Response(
         200,
@@ -350,7 +350,7 @@ async def test_aread():
     assert response.is_closed
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_empty_aread():
     response = httpx.Response(200)
 
@@ -449,7 +449,7 @@ def test_iter_raw_increments_updates_counter():
         num_downloaded = response.num_bytes_downloaded
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_aiter_raw():
     response = httpx.Response(200, content=async_streaming_body())
 
@@ -459,7 +459,7 @@ async def test_aiter_raw():
     assert raw == b"Hello, world!"
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_aiter_raw_with_chunksize():
     response = httpx.Response(200, content=async_streaming_body())
 
@@ -477,7 +477,7 @@ async def test_aiter_raw_with_chunksize():
     assert parts == [b"Hello, world!"]
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_aiter_raw_on_sync():
     response = httpx.Response(
         200,
@@ -488,7 +488,7 @@ async def test_aiter_raw_on_sync():
         [part async for part in response.aiter_raw()]
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_aclose_on_sync():
     response = httpx.Response(
         200,
@@ -499,7 +499,7 @@ async def test_aclose_on_sync():
         await response.aclose()
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_aiter_raw_increments_updates_counter():
     response = httpx.Response(200, content=async_streaming_body())
 
@@ -551,7 +551,7 @@ def streaming_body_with_empty_chunks() -> typing.Iterator[bytes]:
     assert parts == [b"Hello, ", b"world!"]
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_aiter_bytes():
     response = httpx.Response(
         200,
@@ -564,7 +564,7 @@ async def test_aiter_bytes():
     assert content == b"Hello, world!"
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_aiter_bytes_with_chunk_size():
     response = httpx.Response(200, content=async_streaming_body())
     parts = [part async for part in response.aiter_bytes(chunk_size=5)]
@@ -605,7 +605,7 @@ def test_iter_text_with_chunk_size():
     assert parts == ["Hello, world!"]
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_aiter_text():
     response = httpx.Response(
         200,
@@ -618,7 +618,7 @@ async def test_aiter_text():
     assert content == "Hello, world!"
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_aiter_text_with_chunk_size():
     response = httpx.Response(200, content=b"Hello, world!")
     parts = [part async for part in response.aiter_text(chunk_size=5)]
@@ -642,7 +642,7 @@ def test_iter_lines():
     assert content == ["Hello,\n", "world!"]
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_aiter_lines():
     response = httpx.Response(
         200,
@@ -671,7 +671,7 @@ def test_sync_streaming_response():
     assert response.is_closed
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_async_streaming_response():
     response = httpx.Response(
         200,
@@ -702,7 +702,7 @@ def test_cannot_read_after_stream_consumed():
         response.read()
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_cannot_aread_after_stream_consumed():
     response = httpx.Response(
         200,
@@ -728,7 +728,7 @@ def test_cannot_read_after_response_closed():
         response.read()
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_cannot_aread_after_response_closed():
     response = httpx.Response(
         200,
@@ -740,7 +740,7 @@ async def test_cannot_aread_after_response_closed():
         await response.aread()
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_elapsed_not_available_until_closed():
     response = httpx.Response(
         200,
@@ -947,7 +947,7 @@ def test_response_picklable():
     assert pickle_response.history == []
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_response_async_streaming_picklable():
     response = httpx.Response(200, content=async_streaming_body())
     pickle_response = pickle.loads(pickle.dumps(response))
diff --git a/tests/test_asgi.py b/tests/test_asgi.py
index 60f55dfd6f..9c877deaf9 100644
--- a/tests/test_asgi.py
+++ b/tests/test_asgi.py
@@ -70,7 +70,7 @@ async def raise_exc_after_response(scope, receive, send):
     raise RuntimeError()
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_asgi_transport():
     async with httpx.ASGITransport(app=hello_world) as transport:
         request = httpx.Request("GET", "http://www.example.com/")
@@ -80,7 +80,7 @@ async def test_asgi_transport():
         assert response.content == b"Hello, World!"
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_asgi_transport_no_body():
     async with httpx.ASGITransport(app=echo_body) as transport:
         request = httpx.Request("GET", "http://www.example.com/")
@@ -90,7 +90,7 @@ async def test_asgi_transport_no_body():
         assert response.content == b""
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_asgi():
     async with httpx.AsyncClient(app=hello_world) as client:
         response = await client.get("http://www.example.org/")
@@ -99,7 +99,7 @@ async def test_asgi():
     assert response.text == "Hello, World!"
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_asgi_urlencoded_path():
     async with httpx.AsyncClient(app=echo_path) as client:
         url = httpx.URL("http://www.example.org/").copy_with(path="/user@example.org")
@@ -109,7 +109,7 @@ async def test_asgi_urlencoded_path():
     assert response.json() == {"path": "/user@example.org"}
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_asgi_raw_path():
     async with httpx.AsyncClient(app=echo_raw_path) as client:
         url = httpx.URL("http://www.example.org/").copy_with(path="/user@example.org")
@@ -119,7 +119,7 @@ async def test_asgi_raw_path():
     assert response.json() == {"raw_path": "/user%40example.org"}
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_asgi_upload():
     async with httpx.AsyncClient(app=echo_body) as client:
         response = await client.post("http://www.example.org/", content=b"example")
@@ -128,7 +128,7 @@ async def test_asgi_upload():
     assert response.text == "example"
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_asgi_headers():
     async with httpx.AsyncClient(app=echo_headers) as client:
         response = await client.get("http://www.example.org/")
@@ -145,21 +145,21 @@ async def test_asgi_headers():
     }
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_asgi_exc():
     async with httpx.AsyncClient(app=raise_exc) as client:
         with pytest.raises(RuntimeError):
             await client.get("http://www.example.org/")
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_asgi_exc_after_response():
     async with httpx.AsyncClient(app=raise_exc_after_response) as client:
         with pytest.raises(RuntimeError):
             await client.get("http://www.example.org/")
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_asgi_disconnect_after_response_complete():
     disconnect = False
 
diff --git a/tests/test_content.py b/tests/test_content.py
index 6a1303cc80..a4d5f7a1fc 100644
--- a/tests/test_content.py
+++ b/tests/test_content.py
@@ -9,7 +9,7 @@
 url = "https://www.example.com"
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_empty_content():
     request = httpx.Request(method, url)
     assert isinstance(request.stream, httpx.SyncByteStream)
@@ -23,7 +23,7 @@ async def test_empty_content():
     assert async_content == b""
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_bytes_content():
     request = httpx.Request(method, url, content=b"Hello, world!")
     assert isinstance(request.stream, typing.Iterable)
@@ -50,7 +50,7 @@ async def test_bytes_content():
     assert async_content == b"Hello, world!"
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_bytesio_content():
     request = httpx.Request(method, url, content=io.BytesIO(b"Hello, world!"))
     assert isinstance(request.stream, typing.Iterable)
@@ -62,7 +62,7 @@ async def test_bytesio_content():
     assert content == b"Hello, world!"
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_async_bytesio_content():
     class AsyncBytesIO:
         def __init__(self, content: bytes) -> None:
@@ -90,7 +90,7 @@ async def __aiter__(self):
     assert content == b"Hello, world!"
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_iterator_content():
     def hello_world() -> typing.Iterator[bytes]:
         yield b"Hello, "
@@ -126,7 +126,7 @@ def hello_world() -> typing.Iterator[bytes]:
     assert content == b"Hello, world!"
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_aiterator_content():
     async def hello_world() -> typing.AsyncIterator[bytes]:
         yield b"Hello, "
@@ -162,7 +162,7 @@ async def hello_world() -> typing.AsyncIterator[bytes]:
     assert content == b"Hello, world!"
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_json_content():
     request = httpx.Request(method, url, json={"Hello": "world!"})
     assert isinstance(request.stream, typing.Iterable)
@@ -180,7 +180,7 @@ async def test_json_content():
     assert async_content == b'{"Hello": "world!"}'
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_urlencoded_content():
     request = httpx.Request(method, url, data={"Hello": "world!"})
     assert isinstance(request.stream, typing.Iterable)
@@ -198,7 +198,7 @@ async def test_urlencoded_content():
     assert async_content == b"Hello=world%21"
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_urlencoded_boolean():
     request = httpx.Request(method, url, data={"example": True})
     assert isinstance(request.stream, typing.Iterable)
@@ -216,7 +216,7 @@ async def test_urlencoded_boolean():
     assert async_content == b"example=true"
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_urlencoded_none():
     request = httpx.Request(method, url, data={"example": None})
     assert isinstance(request.stream, typing.Iterable)
@@ -234,7 +234,7 @@ async def test_urlencoded_none():
     assert async_content == b"example="
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_urlencoded_list():
     request = httpx.Request(method, url, data={"example": ["a", 1, True]})
     assert isinstance(request.stream, typing.Iterable)
@@ -252,7 +252,7 @@ async def test_urlencoded_list():
     assert async_content == b"example=a&example=1&example=true"
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_multipart_files_content():
     files = {"file": io.BytesIO(b"<file content>")}
     headers = {"Content-Type": "multipart/form-data; boundary=+++"}
@@ -295,7 +295,7 @@ async def test_multipart_files_content():
     )
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_multipart_data_and_files_content():
     data = {"message": "Hello, world!"}
     files = {"file": io.BytesIO(b"<file content>")}
@@ -342,7 +342,7 @@ async def test_multipart_data_and_files_content():
     )
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_empty_request():
     request = httpx.Request(method, url, data={}, files={})
     assert isinstance(request.stream, typing.Iterable)
@@ -364,7 +364,7 @@ def test_invalid_argument():
         httpx.Request(method, url, content={"a": "b"})  # type: ignore
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_multipart_multiple_files_single_input_content():
     files = [
         ("file", io.BytesIO(b"<file content 1>")),
@@ -415,7 +415,7 @@ async def test_multipart_multiple_files_single_input_content():
     )
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_response_empty_content():
     response = httpx.Response(200)
     assert isinstance(response.stream, typing.Iterable)
@@ -429,7 +429,7 @@ async def test_response_empty_content():
     assert async_content == b""
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_response_bytes_content():
     response = httpx.Response(200, content=b"Hello, world!")
     assert isinstance(response.stream, typing.Iterable)
@@ -443,7 +443,7 @@ async def test_response_bytes_content():
     assert async_content == b"Hello, world!"
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_response_iterator_content():
     def hello_world() -> typing.Iterator[bytes]:
         yield b"Hello, "
@@ -462,7 +462,7 @@ def hello_world() -> typing.Iterator[bytes]:
         [part for part in response.stream]
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_response_aiterator_content():
     async def hello_world() -> typing.AsyncIterator[bytes]:
         yield b"Hello, "
diff --git a/tests/test_decoders.py b/tests/test_decoders.py
index 359c1c4b19..35ddad2a82 100644
--- a/tests/test_decoders.py
+++ b/tests/test_decoders.py
@@ -114,7 +114,7 @@ def test_multi_with_identity():
     assert response.content == body
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_streaming():
     body = b"test 123"
     compressor = zlib.compressobj(9, zlib.DEFLATED, zlib.MAX_WBITS | 16)
@@ -173,7 +173,7 @@ def test_decoding_errors(header_value):
         ((b"Accented: \xd6sterreich abcdefghijklmnopqrstuvwxyz", b""), "iso-8859-1"),
     ],
 )
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_text_decoder_with_autodetect(data, encoding):
     async def iterator() -> typing.AsyncIterator[bytes]:
         nonlocal data
@@ -196,7 +196,7 @@ def autodetect(content):
     assert text == (b"".join(data)).decode(encoding)
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_text_decoder_known_encoding():
     async def iterator() -> typing.AsyncIterator[bytes]:
         yield b"\x83g"
diff --git a/tests/test_timeouts.py b/tests/test_timeouts.py
index dee17df2f7..09b25160e7 100644
--- a/tests/test_timeouts.py
+++ b/tests/test_timeouts.py
@@ -3,7 +3,7 @@
 import httpx
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_read_timeout(server):
     timeout = httpx.Timeout(None, read=1e-6)
 
@@ -12,7 +12,7 @@ async def test_read_timeout(server):
             await client.get(server.url.copy_with(path="/slow_response"))
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_write_timeout(server):
     timeout = httpx.Timeout(None, write=1e-6)
 
@@ -22,7 +22,7 @@ async def test_write_timeout(server):
             await client.put(server.url.copy_with(path="/slow_response"), content=data)
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 @pytest.mark.network
 async def test_connect_timeout(server):
     timeout = httpx.Timeout(None, connect=1e-6)
@@ -33,7 +33,7 @@ async def test_connect_timeout(server):
             await client.get("http://10.255.255.1/")
 
 
-@pytest.mark.usefixtures("async_environment")
+@pytest.mark.anyio
 async def test_pool_timeout(server):
     limits = httpx.Limits(max_connections=1)
     timeout = httpx.Timeout(None, pool=1e-4)
diff --git a/tests/test_utils.py b/tests/test_utils.py
index e4bbb6ba2c..859c4e4199 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -98,7 +98,7 @@ def test_parse_header_links(value, expected):
     assert parse_header_links(value) == expected
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_logs_debug(server, capsys):
     with override_log_level("debug"):
         async with httpx.AsyncClient() as client:
@@ -108,7 +108,7 @@ async def test_logs_debug(server, capsys):
     assert 'HTTP Request: GET http://127.0.0.1:8000/ "HTTP/1.1 200 OK"' in stderr
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_logs_trace(server, capsys):
     with override_log_level("trace"):
         async with httpx.AsyncClient() as client:
@@ -118,7 +118,7 @@ async def test_logs_trace(server, capsys):
     assert 'HTTP Request: GET http://127.0.0.1:8000/ "HTTP/1.1 200 OK"' in stderr
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_logs_redirect_chain(server, capsys):
     with override_log_level("debug"):
         async with httpx.AsyncClient(follow_redirects=True) as client: