diff --git a/doc/api/next_api_changes/deprecations/20795-TAC.rst b/doc/api/next_api_changes/deprecations/20795-TAC.rst
new file mode 100644
index 000000000000..ada6992f3483
--- /dev/null
+++ b/doc/api/next_api_changes/deprecations/20795-TAC.rst
@@ -0,0 +1,5 @@
+Remove unused pytest fixture
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+The fixture ``matplotlib.testing.conftest.mpl_image_comparison_parameters``
+is not used internally by Matplotlib.  If you use this please copy it
+into your code base.
diff --git a/lib/matplotlib/testing/conftest.py b/lib/matplotlib/testing/conftest.py
index d0aa85367529..ce1325cd21c9 100644
--- a/lib/matplotlib/testing/conftest.py
+++ b/lib/matplotlib/testing/conftest.py
@@ -97,6 +97,7 @@ def mpl_test_settings(request):
 
 
 @pytest.fixture
+@_api.deprecated("3.5", alternative="none")
 def mpl_image_comparison_parameters(request, extension):
     # This fixture is applied automatically by the image_comparison decorator.
     #
diff --git a/lib/matplotlib/tests/conftest.py b/lib/matplotlib/tests/conftest.py
index 722a7ff91484..f051470f777c 100644
--- a/lib/matplotlib/tests/conftest.py
+++ b/lib/matplotlib/tests/conftest.py
@@ -1,4 +1,3 @@
 from matplotlib.testing.conftest import (mpl_test_settings,
-                                         mpl_image_comparison_parameters,
                                          pytest_configure, pytest_unconfigure,
                                          pd)
diff --git a/lib/mpl_toolkits/tests/conftest.py b/lib/mpl_toolkits/tests/conftest.py
index 81829c903c58..1b48dac4100d 100644
--- a/lib/mpl_toolkits/tests/conftest.py
+++ b/lib/mpl_toolkits/tests/conftest.py
@@ -1,3 +1,2 @@
 from matplotlib.testing.conftest import (mpl_test_settings,
-                                         mpl_image_comparison_parameters,
                                          pytest_configure, pytest_unconfigure)