diff --git a/django/forms/fields.py b/django/forms/fields.py
index 85e7219cd4..66ff1de7fa 100644
--- a/django/forms/fields.py
+++ b/django/forms/fields.py
@@ -10,7 +10,6 @@ import os
 import re
 import sys
 import uuid
-import warnings
 from decimal import Decimal, DecimalException
 from io import BytesIO
 
@@ -513,16 +512,6 @@ class RegexField(CharField):
         'Enter a valid value' is too generic for you.
         """
         kwargs.setdefault('strip', False)
-        # error_message is just kept for backwards compatibility:
-        if error_message is not None:
-            warnings.warn(
-                "The 'error_message' argument is deprecated. Use "
-                "Field.error_messages['invalid'] instead.",
-                RemovedInDjango110Warning, stacklevel=2
-            )
-            error_messages = kwargs.get('error_messages') or {}
-            error_messages['invalid'] = error_message
-            kwargs['error_messages'] = error_messages
         super(RegexField, self).__init__(max_length, min_length, *args, **kwargs)
         self._set_regex(regex)
 
diff --git a/docs/ref/forms/fields.txt b/docs/ref/forms/fields.txt
index 8cdd249005..72ce98d345 100644
--- a/docs/ref/forms/fields.txt
+++ b/docs/ref/forms/fields.txt
@@ -853,14 +853,6 @@ For each field, we describe the default widget used if you don't specify
         Defaults to ``False``. If enabled, stripping will be applied before the
         regex validation.
 
-    .. deprecated:: 1.8
-
-        The optional argument ``error_message`` is also accepted for backwards
-        compatibility but will be removed in Django 1.10. The preferred way to
-        provide an error message is to use the :attr:`~Field.error_messages`
-        argument, passing a dictionary with ``'invalid'`` as a key and the error
-        message as the value.
-
 ``SlugField``
 ~~~~~~~~~~~~~
 
diff --git a/tests/forms_tests/tests/test_fields.py b/tests/forms_tests/tests/test_fields.py
index 9606246bf6..a2caf7ea0c 100644
--- a/tests/forms_tests/tests/test_fields.py
+++ b/tests/forms_tests/tests/test_fields.py
@@ -759,13 +759,6 @@ class FieldsTests(SimpleTestCase):
         self.assertRaisesMessage(ValidationError, "'Enter a valid value.'", f.clean, ' 2A2')
         self.assertRaisesMessage(ValidationError, "'Enter a valid value.'", f.clean, '2A2 ')
 
-    @ignore_warnings(category=RemovedInDjango110Warning)  # error_message deprecation
-    def test_regexfield_4(self):
-        f = RegexField('^[0-9][0-9][0-9][0-9]$', error_message='Enter a four-digit number.')
-        self.assertEqual('1234', f.clean('1234'))
-        self.assertRaisesMessage(ValidationError, "'Enter a four-digit number.'", f.clean, '123')
-        self.assertRaisesMessage(ValidationError, "'Enter a four-digit number.'", f.clean, 'abcd')
-
     def test_regexfield_5(self):
         f = RegexField('^[0-9]+$', min_length=5, max_length=10)
         self.assertRaisesMessage(