diff --git a/pandas/core/frame.py b/pandas/core/frame.py
index 78c9f2aa96472..ade05ab27093e 100644
--- a/pandas/core/frame.py
+++ b/pandas/core/frame.py
@@ -4625,7 +4625,8 @@ def dropna(self, axis=0, how='any', thresh=None, subset=None,
     def drop_duplicates(self, subset=None, keep='first', inplace=False):
         """
         Return DataFrame with duplicate rows removed, optionally only
-        considering certain columns.
+        considering certain columns. Indexes, including time indexes
+        are ignored.
 
         Parameters
         ----------