diff --git a/graphene/utils/str_converters.py b/graphene/utils/str_converters.py
index 2a214f06..f0d41553 100644
--- a/graphene/utils/str_converters.py
+++ b/graphene/utils/str_converters.py
@@ -4,10 +4,22 @@ import re
 # Adapted from this response in Stackoverflow
 # http://stackoverflow.com/a/19053800/1072990
 def to_camel_case(snake_str):
+
+    def _camel_case_convert(components):
+        return components[0] + "".join(x.capitalize() if x else "_" for x in components[1:])
+
+    leading_underscore = False
+    if snake_str.startswith('_'):
+        leading_underscore = True
+        snake_str = snake_str[1:]
+
     components = snake_str.split("_")
+
     # We capitalize the first letter of each component except the first one
     # with the 'capitalize' method and join them together.
-    return components[0] + "".join(x.capitalize() if x else "_" for x in components[1:])
+    if leading_underscore:
+        return "_" + _camel_case_convert(components)
+    return _camel_case_convert(components)
 
 
 # From this response in Stackoverflow
diff --git a/graphene/utils/tests/test_str_converters.py b/graphene/utils/tests/test_str_converters.py
index 307d6877..f37b355a 100644
--- a/graphene/utils/tests/test_str_converters.py
+++ b/graphene/utils/tests/test_str_converters.py
@@ -17,3 +17,4 @@ def test_camel_case():
     assert to_camel_case("snakes_on_a__plane") == "snakesOnA_Plane"
     assert to_camel_case("i_phone_hysteria") == "iPhoneHysteria"
     assert to_camel_case("field_i18n") == "fieldI18n"
+    assert to_camel_case("_private_field") == "_privateField"