diff --git a/lib/matplotlib/offsetbox.py b/lib/matplotlib/offsetbox.py
index 743fccc2bc25..b21f6ddbfb68 100644
--- a/lib/matplotlib/offsetbox.py
+++ b/lib/matplotlib/offsetbox.py
@@ -16,6 +16,7 @@
 
 
 from __future__ import print_function
+import warnings
 import matplotlib.transforms as mtransforms
 import matplotlib.artist as martist
 import matplotlib.text as mtext
@@ -1098,6 +1099,12 @@ def __init__(self, s, loc, pad=0.4, borderpad=0.5, prop=None, **kwargs):
         other keyword parameters of AnchoredOffsetbox are also allowed.
         """
 
+        propkeys = prop.keys()
+        badkwargs = ('ha', 'horizontalalignment', 'va', 'verticalalignment')
+        if set(badkwargs) & set(propkeys):
+            warnings.warn("Mixing horizontalalignment or verticalalignment "
+                    "with AnchoredText is not supported.")
+
         self.txt = TextArea(s, textprops=prop,
                             minimumdescent=False)
         fp = self.txt._text.get_fontproperties()