diff --git a/doc/api/next_api_changes/behaviour.rst b/doc/api/next_api_changes/behaviour.rst
index b8a77d56e813..9ebe3fe42240 100644
--- a/doc/api/next_api_changes/behaviour.rst
+++ b/doc/api/next_api_changes/behaviour.rst
@@ -150,3 +150,8 @@ support for it will be dropped in a future Matplotlib release.
 `.font_manager.json_dump` now locks the font manager dump file
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 ... to prevent multiple processes from writing to it at the same time.
+
+`.pyplot.rgrids` and `.pyplot.thetagrids` now act as setters also when called with only kwargs
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Previously, keyword arguments were silently ignored when no positional
+arguments were given.
diff --git a/lib/matplotlib/pyplot.py b/lib/matplotlib/pyplot.py
index 898d4b3f1383..3d7dd1c0ac0c 100644
--- a/lib/matplotlib/pyplot.py
+++ b/lib/matplotlib/pyplot.py
@@ -1627,7 +1627,7 @@ def rgrids(*args, **kwargs):
     ax = gca()
     if not isinstance(ax, PolarAxes):
         raise RuntimeError('rgrids only defined for polar axes')
-    if len(args) == 0:
+    if not args and not kwargs:
         lines = ax.yaxis.get_gridlines()
         labels = ax.yaxis.get_ticklabels()
     else:
@@ -1694,7 +1694,7 @@ def thetagrids(*args, **kwargs):
     ax = gca()
     if not isinstance(ax, PolarAxes):
         raise RuntimeError('thetagrids only defined for polar axes')
-    if len(args) == 0:
+    if not args and not kwargs:
         lines = ax.xaxis.get_ticklines()
         labels = ax.xaxis.get_ticklabels()
     else: