diff --git a/pandas/tests/frame/test_analytics.py b/pandas/tests/frame/test_analytics.py
index e99208ac78e15..f694689fa9dfb 100644
--- a/pandas/tests/frame/test_analytics.py
+++ b/pandas/tests/frame/test_analytics.py
@@ -1,4 +1,5 @@
 from datetime import timedelta
+from decimal import Decimal
 import operator
 from string import ascii_lowercase
 import warnings
@@ -1075,6 +1076,29 @@ def test_mean_excludeds_datetimes(self, tz):
         expected = pd.Series()
         tm.assert_series_equal(result, expected)
 
+    def test_mean_mixed_string_decimal(self):
+        # GH 11670
+        # possible bug when calculating mean of DataFrame?
+
+        d = [
+            {"A": 2, "B": None, "C": Decimal("628.00")},
+            {"A": 1, "B": None, "C": Decimal("383.00")},
+            {"A": 3, "B": None, "C": Decimal("651.00")},
+            {"A": 2, "B": None, "C": Decimal("575.00")},
+            {"A": 4, "B": None, "C": Decimal("1114.00")},
+            {"A": 1, "B": "TEST", "C": Decimal("241.00")},
+            {"A": 2, "B": None, "C": Decimal("572.00")},
+            {"A": 4, "B": None, "C": Decimal("609.00")},
+            {"A": 3, "B": None, "C": Decimal("820.00")},
+            {"A": 5, "B": None, "C": Decimal("1223.00")},
+        ]
+
+        df = pd.DataFrame(d)
+
+        result = df.mean()
+        expected = pd.Series([2.7, 681.6], index=["A", "C"])
+        tm.assert_series_equal(result, expected)
+
     def test_var_std(self, datetime_frame):
         result = datetime_frame.std(ddof=4)
         expected = datetime_frame.apply(lambda x: x.std(ddof=4))