diff --git a/tests/test_panel_daily_bar_reader.py b/tests/test_panel_daily_bar_reader.py
new file mode 100644
index 00000000..178a4553
--- /dev/null
+++ b/tests/test_panel_daily_bar_reader.py
@@ -0,0 +1,48 @@
+#
+# Copyright 2016 Quantopian, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from itertools import permutations
+
+import pandas as pd
+
+from zipline.data.us_equity_pricing import PanelDailyBarReader
+from zipline.testing import ExplodingObject
+from zipline.testing.fixtures import ZiplineTestCase
+
+
+class TestPanelDailyBarReader(ZiplineTestCase):
+    def test_duplicate_values(self):
+        UNIMPORTANT_VALUE = 57
+
+        panel = pd.Panel(
+            UNIMPORTANT_VALUE,
+            items=['a', 'b', 'b', 'a'],
+            major_axis=['c'],
+            minor_axis=['d'],
+        )
+        unused = ExplodingObject()
+
+        axis_names = ['items', 'major_axis', 'minor_axis']
+
+        for axis_order in permutations((0, 1, 2)):
+            with self.assertRaises(ValueError) as e:
+                PanelDailyBarReader(unused, panel.transpose(*axis_order))
+
+            expected = (
+                "Duplicate entries in Panel.{name}: ['a', 'b'].".format(
+                    name=axis_names[axis_order.index(0)],
+                )
+            )
+            self.assertEqual(str(e.exception), expected)
diff --git a/zipline/data/us_equity_pricing.py b/zipline/data/us_equity_pricing.py
index fbfb1a06..197b74ca 100644
--- a/zipline/data/us_equity_pricing.py
+++ b/zipline/data/us_equity_pricing.py
@@ -54,10 +54,12 @@ from six import (
 )
 
 from zipline.utils.functional import apply
+from zipline.utils.preprocess import call
 from zipline.utils.input_validation import (
     coerce_string,
     preprocess,
     expect_element,
+    verify_indices_all_unique,
 )
 from zipline.utils.sqlite_utils import group_into_chunks
 from zipline.utils.memoize import lazyval
@@ -696,9 +698,12 @@ class PanelDailyBarReader(DailyBarReader):
 
     DataPanel Structure
     -------
-    items : Int64Index, asset identifiers
-    major_axis : DatetimeIndex, days provided by the Panel.
+    items : Int64Index
+        Asset identifiers.  Must be unique.
+    major_axis : DatetimeIndex
+       Dates for data provided provided by the Panel.  Must be unique.
     minor_axis : ['open', 'high', 'low', 'close', 'volume']
+       Price attributes.  Must be unique.
 
     Attributes
     ----------
@@ -710,7 +715,9 @@ class PanelDailyBarReader(DailyBarReader):
     first_trading_day : pd.Timestamp
         The first trading day in the dataset.
     """
+    @preprocess(panel=call(verify_indices_all_unique))
     def __init__(self, calendar, panel):
+
         panel = panel.copy()
         if 'volume' not in panel.items:
             # Fake volume if it does not exist.
@@ -760,7 +767,7 @@ class PanelDailyBarReader(DailyBarReader):
             Returns -1 if the day is within the date range, but the price is
             0.
         """
-        return self.panel[sid, day, colname]
+        return self.panel.loc[sid, day, colname]
 
     def get_last_traded_dt(self, sid, dt):
         """
diff --git a/zipline/utils/input_validation.py b/zipline/utils/input_validation.py
index 0424e6f4..840ec5b6 100644
--- a/zipline/utils/input_validation.py
+++ b/zipline/utils/input_validation.py
@@ -26,6 +26,43 @@ from zipline.utils.functional import getattrs
 from zipline.utils.preprocess import call, preprocess
 
 
+def verify_indices_all_unique(obj):
+    """
+    Check that all axes of a pandas object are unique.
+
+    Parameters
+    ----------
+    obj : pd.Series / pd.DataFrame / pd.Panel
+        The object to validate.
+
+    Returns
+    -------
+    None
+
+    Raises
+    ------
+    ValueError
+        If any axis has duplicate entries.
+    """
+    axis_names = [
+        ('index',),                            # Series
+        ('index', 'columns'),                  # DataFrame
+        ('items', 'major_axis', 'minor_axis')  # Panel
+    ][obj.ndim - 1]  # ndim = 1 should go to entry 0,
+
+    for axis_name, index in zip(axis_names, obj.axes):
+        if index.is_unique:
+            continue
+
+        raise ValueError(
+            "Duplicate entries in {type}.{axis}: {dupes}.".format(
+                type=type(obj).__name__,
+                axis=axis_name,
+                dupes=sorted(index[index.duplicated()]),
+            )
+        )
+
+
 def optionally(preprocessor):
     """Modify a preprocessor to explicitly allow `None`.