diff --git a/lib/matplotlib/animation.py b/lib/matplotlib/animation.py
index de2d17a30eae..63f8727c9e32 100644
--- a/lib/matplotlib/animation.py
+++ b/lib/matplotlib/animation.py
@@ -952,7 +952,10 @@ class FuncAnimation(TimedAnimation):
 
     *init_func* is a function used to draw a clear frame. If not given, the
     results of drawing from the first item in the frames sequence will be
-    used.
+    used. This function will be called once before the first frame. 
+
+    If blit=True, *func* and *init_func* should return an iterable of
+    drawables to clear.
     '''
     def __init__(self, fig, func, frames=None, init_func=None, fargs=None,
             save_count=None, **kwargs):