diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 5d2a0fe66cc1d..4c962da3c8d1e 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -7873,6 +7873,12 @@ def isna(self: NDFrameT) -> NDFrameT:
         strings ``''`` or :attr:`numpy.inf` are not considered NA values
         (unless you set ``pandas.options.mode.use_inf_as_na = True``).
 
+        Note: For nullable float extension dtypes, i.e.
+        ``Float<...>`` and ``float<...>[pyarrow]``, the behavior is different -
+        missing data is designated by ``pandas.NA`` values while NaN may also be
+        stored but will **not** get mapped to True (these values can be detected
+        by :func:`numpy.isnan`).
+
         Returns
         -------
         {klass}