Index: django/forms/fields.py
===================================================================
--- django/forms/fields.py	(revision 8983)
+++ django/forms/fields.py	(working copy)
@@ -379,6 +379,10 @@
         if isinstance(value, list):
             # Input comes from a SplitDateTimeWidget, for example. So, it's two
             # components: date and time.
+            if not [v for v in value if v not in EMPTY_VALUES]:
+                if self.required:
+                    raise ValidationError(self.error_messages['required'])
+                return None
             if len(value) != 2:
                 raise ValidationError(self.error_messages['invalid'])
             value = '%s %s' % tuple(value)
Index: tests/regressiontests/forms/fields.py
===================================================================
--- tests/regressiontests/forms/fields.py	(revision 8983)
+++ tests/regressiontests/forms/fields.py	(working copy)
@@ -619,6 +619,16 @@
 >>> repr(f.clean(''))
 'None'
 
+Regression test for #8898.
+>>> f = DateTimeField(widget=SplitDateTimeWidget)
+>>> f.clean(['', ''])
+Traceback (most recent call last):
+...
+ValidationError: [u'This field is required.']
+>>> f = DateTimeField(required=False, widget=SplitDateTimeWidget)
+>>> repr(f.clean(['', '']))
+'None'
+
 # RegexField ##################################################################
 
 >>> f = RegexField('^\d[A-F]\d$')
Index: AUTHORS
===================================================================
--- AUTHORS	(revision 8983)
+++ AUTHORS	(working copy)
@@ -239,6 +239,7 @@
     Eugene Lazutkin <http://lazutkin.com/blog/>
     lcordier@point45.com
     Jeong-Min Lee <falsetru@gmail.com>
+    Tai Lee <real.human@mrmachine.net>
     Jannis Leidel <jl@websushi.org>
     Christopher Lenz <http://www.cmlenz.net/>
     lerouxb@gmail.com
@@ -278,7 +279,6 @@
     Aljosa Mohorovic <aljosa.mohorovic@gmail.com>
     Ramiro Morales <rm0@gmx.net>
     Eric Moritz <http://eric.themoritzfamily.com/>
-    mrmachine <real.human@mrmachine.net>
     Robin Munn <http://www.geekforgod.com/>
     James Murty
     msundstr