diff --git a/pandas_gbq/schema.py b/pandas_gbq/schema.py
index cfa1c765..d3357719 100644
--- a/pandas_gbq/schema.py
+++ b/pandas_gbq/schema.py
@@ -116,7 +116,7 @@ def generate_bq_schema(dataframe, default_type="STRING"):
     }
 
     fields = []
-    for column_name, dtype in dataframe.dtypes.iteritems():
+    for column_name, dtype in dataframe.dtypes.items():
         fields.append(
             {"name": column_name, "type": type_mapping.get(dtype.kind, default_type)}
         )