diff --git a/graphene/test/__init__.py b/graphene/test/__init__.py
index dab3b51b..4d2e4df0 100644
--- a/graphene/test/__init__.py
+++ b/graphene/test/__init__.py
@@ -1,5 +1,4 @@
 from promise import Promise, is_thenable
-import six
 from graphql.error import format_error as format_graphql_error
 from graphql.error import GraphQLError
 
@@ -10,7 +9,7 @@ def default_format_error(error):
     if isinstance(error, GraphQLError):
         return format_graphql_error(error)
 
-    return {"message": six.text_type(error)}
+    return {"message": str(error)}
 
 
 def format_execution_result(execution_result, format_error):
diff --git a/graphene/types/datetime.py b/graphene/types/datetime.py
index 3519d76d..ca96547f 100644
--- a/graphene/types/datetime.py
+++ b/graphene/types/datetime.py
@@ -4,7 +4,6 @@ import datetime
 
 from aniso8601 import parse_date, parse_datetime, parse_time
 from graphql.language import ast
-from six import string_types
 
 from .scalars import Scalar
 
@@ -35,7 +34,7 @@ class Date(Scalar):
         try:
             if isinstance(value, datetime.date):
                 return value
-            elif isinstance(value, string_types):
+            elif isinstance(value, str):
                 return parse_date(value)
         except ValueError:
             return None
@@ -65,7 +64,7 @@ class DateTime(Scalar):
         try:
             if isinstance(value, datetime.datetime):
                 return value
-            elif isinstance(value, string_types):
+            elif isinstance(value, str):
                 return parse_datetime(value)
         except ValueError:
             return None
@@ -95,7 +94,7 @@ class Time(Scalar):
         try:
             if isinstance(value, datetime.time):
                 return value
-            elif isinstance(value, string_types):
+            elif isinstance(value, str):
                 return parse_time(value)
         except ValueError:
             return None
diff --git a/graphene/types/scalars.py b/graphene/types/scalars.py
index a5596d28..b9cb1aa0 100644
--- a/graphene/types/scalars.py
+++ b/graphene/types/scalars.py
@@ -1,4 +1,3 @@
-import six
 from typing import Any
 
 from graphql.language.ast import BooleanValue, FloatValue, IntValue, StringValue
@@ -113,7 +112,7 @@ class String(Scalar):
     def coerce_string(value):
         if isinstance(value, bool):
             return u"true" if value else u"false"
-        return six.text_type(value)
+        return str(value)
 
     serialize = coerce_string
     parse_value = coerce_string
diff --git a/graphene/types/utils.py b/graphene/types/utils.py
index b026355b..a7e23572 100644
--- a/graphene/types/utils.py
+++ b/graphene/types/utils.py
@@ -2,8 +2,6 @@ import inspect
 from collections import OrderedDict
 from functools import partial
 
-from six import string_types
-
 from ..utils.module_loading import import_string
 from .mountedtype import MountedType
 from .unmountedtype import UnmountedType
@@ -39,7 +37,7 @@ def yank_fields_from_attrs(attrs, _as=None, sort=True):
 
 
 def get_type(_type):
-    if isinstance(_type, string_types):
+    if isinstance(_type, str):
         return import_string(_type)
     if inspect.isfunction(_type) or isinstance(_type, partial):
         return _type()
diff --git a/graphene/types/uuid.py b/graphene/types/uuid.py
index b9687e1e..f55e7a85 100644
--- a/graphene/types/uuid.py
+++ b/graphene/types/uuid.py
@@ -1,5 +1,4 @@
 from __future__ import absolute_import
-import six
 from uuid import UUID as _UUID
 
 from graphql.language import ast
@@ -12,7 +11,7 @@ class UUID(Scalar):
 
     @staticmethod
     def serialize(uuid):
-        if isinstance(uuid, six.string_types):
+        if isinstance(uuid, str):
             uuid = _UUID(uuid)
 
         assert isinstance(uuid, _UUID), "Expected UUID instance, received {}".format(