diff --git a/django/utils/dateparse.py b/django/utils/dateparse.py
index 535655561c..0945c0c761 100644
--- a/django/utils/dateparse.py
+++ b/django/utils/dateparse.py
@@ -16,13 +16,13 @@ date_re = _lazy_re_compile(
 
 time_re = _lazy_re_compile(
     r'(?P<hour>\d{1,2}):(?P<minute>\d{1,2})'
-    r'(?::(?P<second>\d{1,2})(?:\.(?P<microsecond>\d{1,6})\d{0,6})?)?'
+    r'(?::(?P<second>\d{1,2})(?:[\.,](?P<microsecond>\d{1,6})\d{0,6})?)?'
 )
 
 datetime_re = _lazy_re_compile(
     r'(?P<year>\d{4})-(?P<month>\d{1,2})-(?P<day>\d{1,2})'
     r'[T ](?P<hour>\d{1,2}):(?P<minute>\d{1,2})'
-    r'(?::(?P<second>\d{1,2})(?:\.(?P<microsecond>\d{1,6})\d{0,6})?)?'
+    r'(?::(?P<second>\d{1,2})(?:[\.,](?P<microsecond>\d{1,6})\d{0,6})?)?'
     r'(?P<tzinfo>Z|[+-]\d{2}(?::?\d{2})?)?$'
 )
 
@@ -33,7 +33,7 @@ standard_duration_re = _lazy_re_compile(
     r'((?:(?P<hours>\d+):)(?=\d+:\d+))?'
     r'(?:(?P<minutes>\d+):)?'
     r'(?P<seconds>\d+)'
-    r'(?:\.(?P<microseconds>\d{1,6})\d{0,6})?'
+    r'(?:[\.,](?P<microseconds>\d{1,6})\d{0,6})?'
     r'$'
 )
 
diff --git a/docs/ref/utils.txt b/docs/ref/utils.txt
index 8aa8c3403d..33afbac36a 100644
--- a/docs/ref/utils.txt
+++ b/docs/ref/utils.txt
@@ -139,6 +139,10 @@ The functions defined in this module share the following properties:
     UTC offsets aren't supported; if ``value`` describes one, the result is
     ``None``.
 
+    .. versionchanged:: 3.1
+
+        Support for comma separators for milliseconds was added.
+
 .. function:: parse_datetime(value)
 
     Parses a string and returns a :class:`datetime.datetime`.
@@ -146,18 +150,23 @@ The functions defined in this module share the following properties:
     UTC offsets are supported; if ``value`` describes one, the result's
     ``tzinfo`` attribute is a :class:`datetime.timezone` instance.
 
+    .. versionchanged:: 3.1
+
+        Support for comma separators for milliseconds was added.
+
 .. function:: parse_duration(value)
 
     Parses a string and returns a :class:`datetime.timedelta`.
 
-    Expects data in the format ``"DD HH:MM:SS.uuuuuu"`` or as specified by ISO
-    8601 (e.g. ``P4DT1H15M20S`` which is equivalent to ``4 1:15:20``) or
-    PostgreSQL's day-time interval format (e.g. ``3 days 04:05:06``).
+    Expects data in the format ``"DD HH:MM:SS.uuuuuu"``,
+    ``"DD HH:MM:SS,uuuuuu"``,  or as specified by ISO 8601 (e.g.
+    ``P4DT1H15M20S`` which is equivalent to ``4 1:15:20``) or PostgreSQL's
+    day-time interval format (e.g. ``3 days 04:05:06``).
 
     .. versionchanged:: 3.1
 
         Support for comma separators for decimal fractions in the ISO 8601
-        format was added.
+        format and for the format ``"DD HH:MM:SS,uuuuuu"`` was added.
 
 ``django.utils.decorators``
 ===========================
diff --git a/docs/releases/3.1.txt b/docs/releases/3.1.txt
index ed841cc962..dc16b95f79 100644
--- a/docs/releases/3.1.txt
+++ b/docs/releases/3.1.txt
@@ -259,6 +259,11 @@ Utilities
 * :func:`~django.utils.dateparse.parse_duration` now supports comma separators
   for decimal fractions in the ISO 8601 format.
 
+* :func:`~django.utils.dateparse.parse_datetime`,
+  :func:`~django.utils.dateparse.parse_duration`, and
+  :func:`~django.utils.dateparse.parse_time` now support comma separators for
+  milliseconds.
+
 Validators
 ~~~~~~~~~~
 
diff --git a/tests/utils_tests/test_dateparse.py b/tests/utils_tests/test_dateparse.py
index b1b591a7df..844b7e4ab7 100644
--- a/tests/utils_tests/test_dateparse.py
+++ b/tests/utils_tests/test_dateparse.py
@@ -23,6 +23,7 @@ class DateParseTests(unittest.TestCase):
         self.assertEqual(parse_time('09:15:00'), time(9, 15))
         self.assertEqual(parse_time('10:10'), time(10, 10))
         self.assertEqual(parse_time('10:20:30.400'), time(10, 20, 30, 400000))
+        self.assertEqual(parse_time('10:20:30,400'), time(10, 20, 30, 400000))
         self.assertEqual(parse_time('4:8:16'), time(4, 8, 16))
         # Invalid inputs
         self.assertIsNone(parse_time('091500'))
@@ -38,6 +39,7 @@ class DateParseTests(unittest.TestCase):
             ('2012-04-23T10:20:30.400+02:30', datetime(2012, 4, 23, 10, 20, 30, 400000, get_fixed_timezone(150))),
             ('2012-04-23T10:20:30.400+02', datetime(2012, 4, 23, 10, 20, 30, 400000, get_fixed_timezone(120))),
             ('2012-04-23T10:20:30.400-02', datetime(2012, 4, 23, 10, 20, 30, 400000, get_fixed_timezone(-120))),
+            ('2012-04-23T10:20:30,400-02', datetime(2012, 4, 23, 10, 20, 30, 400000, get_fixed_timezone(-120))),
         )
         for source, expected in valid_inputs:
             with self.subTest(source=source):
@@ -104,6 +106,7 @@ class DurationParseTests(unittest.TestCase):
             ('15:30.0001', timedelta(minutes=15, seconds=30, microseconds=100)),
             ('15:30.00001', timedelta(minutes=15, seconds=30, microseconds=10)),
             ('15:30.000001', timedelta(minutes=15, seconds=30, microseconds=1)),
+            ('15:30,000001', timedelta(minutes=15, seconds=30, microseconds=1)),
         )
         for source, expected in test_values:
             with self.subTest(source=source):
@@ -116,6 +119,7 @@ class DurationParseTests(unittest.TestCase):
             ('-15:30', timedelta(minutes=-15, seconds=-30)),
             ('-1:15:30', timedelta(hours=-1, minutes=-15, seconds=-30)),
             ('-30.1', timedelta(seconds=-30, milliseconds=-100)),
+            ('-30,1', timedelta(seconds=-30, milliseconds=-100)),
             ('-00:01:01', timedelta(minutes=-1, seconds=-1)),
             ('-01:01', timedelta(seconds=-61)),
             ('-01:-01', None),