diff --git a/tests/asyncio/future/test_async_future.py b/tests/asyncio/future/test_async_future.py
index 3322cb05..cd50b6fa 100644
--- a/tests/asyncio/future/test_async_future.py
+++ b/tests/asyncio/future/test_async_future.py
@@ -14,7 +14,10 @@
 
 import asyncio
 
-import mock
+try:
+    from unittest import mock
+except:
+    import mock
 import pytest
 
 from google.api_core import exceptions
diff --git a/tests/asyncio/gapic/test_method_async.py b/tests/asyncio/gapic/test_method_async.py
index 7318362b..1c12a672 100644
--- a/tests/asyncio/gapic/test_method_async.py
+++ b/tests/asyncio/gapic/test_method_async.py
@@ -15,7 +15,10 @@
 import datetime
 
 from grpc.experimental import aio
-import mock
+try:
+    from unittest import mock
+except:
+    import mock
 import pytest
 
 from google.api_core import (exceptions, gapic_v1, grpc_helpers_async,
diff --git a/tests/asyncio/operations_v1/test_operations_async_client.py b/tests/asyncio/operations_v1/test_operations_async_client.py
index a6469016..1b0e3d0e 100644
--- a/tests/asyncio/operations_v1/test_operations_async_client.py
+++ b/tests/asyncio/operations_v1/test_operations_async_client.py
@@ -13,7 +13,10 @@
 # limitations under the License.
 
 from grpc.experimental import aio
-import mock
+try:
+    from unittest import mock
+except:
+    import mock
 import pytest
 
 from google.api_core import (grpc_helpers_async, operations_v1,
diff --git a/tests/asyncio/test_grpc_helpers_async.py b/tests/asyncio/test_grpc_helpers_async.py
index 868018cf..312c54b0 100644
--- a/tests/asyncio/test_grpc_helpers_async.py
+++ b/tests/asyncio/test_grpc_helpers_async.py
@@ -14,7 +14,10 @@
 
 import grpc
 from grpc.experimental import aio
-import mock
+try:
+    from unittest import mock
+except:
+    import mock
 import pytest
 
 from google.api_core import exceptions
diff --git a/tests/asyncio/test_operation_async.py b/tests/asyncio/test_operation_async.py
index e35d1396..9b2294cc 100644
--- a/tests/asyncio/test_operation_async.py
+++ b/tests/asyncio/test_operation_async.py
@@ -13,7 +13,10 @@
 # limitations under the License.
 
 
-import mock
+try:
+    from unittest import mock
+except:
+    import mock
 import pytest
 
 from google.api_core import exceptions
diff --git a/tests/asyncio/test_page_iterator_async.py b/tests/asyncio/test_page_iterator_async.py
index 4abacc6a..25fb76fb 100644
--- a/tests/asyncio/test_page_iterator_async.py
+++ b/tests/asyncio/test_page_iterator_async.py
@@ -14,7 +14,10 @@
 
 import inspect
 
-import mock
+try:
+    from unittest import mock
+except:
+    import mock
 import pytest
 
 from google.api_core import page_iterator_async
diff --git a/tests/asyncio/test_retry_async.py b/tests/asyncio/test_retry_async.py
index 8f863668..1656669e 100644
--- a/tests/asyncio/test_retry_async.py
+++ b/tests/asyncio/test_retry_async.py
@@ -15,7 +15,10 @@
 import datetime
 import re
 
-import mock
+try:
+    from unittest import mock
+except:
+    import mock
 import pytest
 
 from google.api_core import exceptions
diff --git a/tests/unit/future/test__helpers.py b/tests/unit/future/test__helpers.py
index 98afc599..1d15e66d 100644
--- a/tests/unit/future/test__helpers.py
+++ b/tests/unit/future/test__helpers.py
@@ -12,7 +12,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import mock
+try:
+    from unittest import mock
+except:
+    import mock
 
 from google.api_core.future import _helpers
 
diff --git a/tests/unit/future/test_polling.py b/tests/unit/future/test_polling.py
index 2381d036..cc59744e 100644
--- a/tests/unit/future/test_polling.py
+++ b/tests/unit/future/test_polling.py
@@ -16,7 +16,10 @@
 import threading
 import time
 
-import mock
+try:
+    from unittest import mock
+except:
+    import mock
 import pytest
 
 from google.api_core import exceptions, retry
diff --git a/tests/unit/gapic/test_method.py b/tests/unit/gapic/test_method.py
index 1ae27de0..9ab7b390 100644
--- a/tests/unit/gapic/test_method.py
+++ b/tests/unit/gapic/test_method.py
@@ -14,7 +14,10 @@
 
 import datetime
 
-import mock
+try:
+    from unittest import mock
+except:
+    import mock
 
 from google.api_core import exceptions
 from google.api_core import retry
diff --git a/tests/unit/test_bidi.py b/tests/unit/test_bidi.py
index 52215cbd..9f497515 100644
--- a/tests/unit/test_bidi.py
+++ b/tests/unit/test_bidi.py
@@ -17,7 +17,10 @@
 import threading
 
 import grpc
-import mock
+try:
+    from unittest import mock
+except:
+    import mock
 import pytest
 from six.moves import queue
 
diff --git a/tests/unit/test_exceptions.py b/tests/unit/test_exceptions.py
index fb29015f..c6d4d802 100644
--- a/tests/unit/test_exceptions.py
+++ b/tests/unit/test_exceptions.py
@@ -15,7 +15,10 @@
 import json
 
 import grpc
-import mock
+try:
+    from unittest import mock
+except:
+    import mock
 import requests
 from six.moves import http_client
 
diff --git a/tests/unit/test_grpc_helpers.py b/tests/unit/test_grpc_helpers.py
index 8c6202bc..9bb37567 100644
--- a/tests/unit/test_grpc_helpers.py
+++ b/tests/unit/test_grpc_helpers.py
@@ -13,7 +13,10 @@
 # limitations under the License.
 
 import grpc
-import mock
+try:
+    from unittest import mock
+except:
+    import mock
 import pytest
 
 from google.api_core import exceptions
diff --git a/tests/unit/test_operation.py b/tests/unit/test_operation.py
index ae9bafea..d3f0e423 100644
--- a/tests/unit/test_operation.py
+++ b/tests/unit/test_operation.py
@@ -13,7 +13,10 @@
 # limitations under the License.
 
 
-import mock
+try:
+    from unittest import mock
+except:
+    import mock
 
 from google.api_core import exceptions
 from google.api_core import operation
diff --git a/tests/unit/test_page_iterator.py b/tests/unit/test_page_iterator.py
index 97b0657b..d78d2502 100644
--- a/tests/unit/test_page_iterator.py
+++ b/tests/unit/test_page_iterator.py
@@ -15,7 +15,10 @@
 import math
 import types
 
-import mock
+try:
+    from unittest import mock
+except:
+    import mock
 import pytest
 import six
 
diff --git a/tests/unit/test_path_template.py b/tests/unit/test_path_template.py
index 4c8a7c5e..4dae8982 100644
--- a/tests/unit/test_path_template.py
+++ b/tests/unit/test_path_template.py
@@ -14,7 +14,10 @@
 
 from __future__ import unicode_literals
 
-import mock
+try:
+    from unittest import mock
+except:
+    import mock
 import pytest
 
 from google.api_core import path_template
diff --git a/tests/unit/test_retry.py b/tests/unit/test_retry.py
index ce8f417d..758648e0 100644
--- a/tests/unit/test_retry.py
+++ b/tests/unit/test_retry.py
@@ -16,7 +16,10 @@
 import itertools
 import re
 
-import mock
+try:
+    from unittest import mock
+except:
+    import mock
 import pytest
 import requests.exceptions
 
diff --git a/tests/unit/test_timeout.py b/tests/unit/test_timeout.py
index 30d624e2..01d0e5b6 100644
--- a/tests/unit/test_timeout.py
+++ b/tests/unit/test_timeout.py
@@ -15,7 +15,10 @@
 import datetime
 import itertools
 
-import mock
+try:
+    from unittest import mock
+except:
+    import mock
 
 from google.api_core import timeout