diff --git a/django/forms/formsets.py b/django/forms/formsets.py
index 42d25fa..0574daa 100644
--- a/django/forms/formsets.py
+++ b/django/forms/formsets.py
@@ -175,11 +175,10 @@ class BaseFormSet(object):
     @property
     def deleted_forms(self):
         """
-        Returns a list of forms that have been marked for deletion. Raises an
-        AttributeError if deletion is not allowed.
+        Returns a list of forms that have been marked for deletion.
         """
         if not self.is_valid() or not self.can_delete:
-            raise AttributeError("'%s' object has no attribute 'deleted_forms'" % self.__class__.__name__)
+            return []
         # construct _deleted_form_indexes which is just a list of form indexes
         # that have had their deletion widget set to True
         if not hasattr(self, '_deleted_form_indexes'):
diff --git a/django/forms/models.py b/django/forms/models.py
index 1aa49ea..e0822ed 100644
--- a/django/forms/models.py
+++ b/django/forms/models.py
@@ -500,9 +500,9 @@ class BaseModelFormSet(BaseFormSet):
         # Collect unique_checks and date_checks to run from all the forms.
         all_unique_checks = set()
         all_date_checks = set()
-        for form in self.forms:
-            if not form.is_valid():
-                continue
+        forms_to_delete = self.deleted_forms
+        valid_forms = [form for form in self.forms if form.is_valid() and form not in forms_to_delete]
+        for form in valid_forms:
             exclude = form._get_validation_exclusions()
             unique_checks, date_checks = form.instance._get_unique_checks(exclude=exclude)
             all_unique_checks = all_unique_checks.union(set(unique_checks))
@@ -512,9 +512,7 @@ class BaseModelFormSet(BaseFormSet):
         # Do each of the unique checks (unique and unique_together)
         for uclass, unique_check in all_unique_checks:
             seen_data = set()
-            for form in self.forms:
-                if not form.is_valid():
-                    continue
+            for form in valid_forms:
                 # get data for each field of each of unique_check
                 row_data = tuple([form.cleaned_data[field] for field in unique_check if field in form.cleaned_data])
                 if row_data and not None in row_data:
@@ -534,9 +532,7 @@ class BaseModelFormSet(BaseFormSet):
         for date_check in all_date_checks:
             seen_data = set()
             uclass, lookup, field, unique_for = date_check
-            for form in self.forms:
-                if not form.is_valid():
-                    continue
+            for form in valid_forms:
                 # see if we have data for both fields
                 if (form.cleaned_data and form.cleaned_data[field] is not None
                     and form.cleaned_data[unique_for] is not None):
@@ -591,10 +587,7 @@ class BaseModelFormSet(BaseFormSet):
             return []
 
         saved_instances = []
-        try:
-            forms_to_delete = self.deleted_forms
-        except AttributeError:
-            forms_to_delete = []
+        forms_to_delete = self.deleted_forms
         for form in self.initial_forms:
             pk_name = self._pk_field.name
             raw_pk_value = form._raw_value(pk_name)
diff --git a/tests/modeltests/model_formsets/tests.py b/tests/modeltests/model_formsets/tests.py
index e28560b..f3a8618 100644
--- a/tests/modeltests/model_formsets/tests.py
+++ b/tests/modeltests/model_formsets/tests.py
@@ -42,21 +42,29 @@ class DeletionTests(TestCase):
         doesn't cause validation errors.
         """
         PoetFormSet = modelformset_factory(Poet, can_delete=True)
+        poet = Poet.objects.create(name='test')
+        # One existing untouched and two new unvalid forms
         data = {
-            'form-TOTAL_FORMS': '1',
-            'form-INITIAL_FORMS': '0',
+            'form-TOTAL_FORMS': '3',
+            'form-INITIAL_FORMS': '1',
             'form-MAX_NUM_FORMS': '0',
-            'form-0-id': '',
-            'form-0-name': 'x' * 1000,
+            'form-0-id': six.text_type(poet.id),
+            'form-0-name': 'test',
+            'form-1-id': '',
+            'form-1-name': 'x' * 1000, # Too long
+            'form-1-id': six.text_type(poet.id), # Violate unique constraint
+            'form-1-name': 'test2',
         }
         formset = PoetFormSet(data, queryset=Poet.objects.all())
         # Make sure this form doesn't pass validation.
         self.assertEqual(formset.is_valid(), False)
-        self.assertEqual(Poet.objects.count(), 0)
+        self.assertEqual(Poet.objects.count(), 1)
 
         # Then make sure that it *does* pass validation and delete the object,
-        # even though the data isn't actually valid.
+        # even though the data in new forms aren't actually valid.
         data['form-0-DELETE'] = 'on'
+        data['form-1-DELETE'] = 'on'
+        data['form-2-DELETE'] = 'on'
         formset = PoetFormSet(data, queryset=Poet.objects.all())
         self.assertEqual(formset.is_valid(), True)
         formset.save()
@@ -64,7 +72,7 @@ class DeletionTests(TestCase):
 
     def test_change_form_deletion_when_invalid(self):
         """
-        Make sure that an add form that is filled out, but marked for deletion
+        Make sure that a change form that is filled out, but marked for deletion
         doesn't cause validation errors.
         """
         PoetFormSet = modelformset_factory(Poet, can_delete=True)
