diff --git a/pandas_schema/validation.py b/pandas_schema/validation.py
index f3cfab3..5b7d0f9 100644
--- a/pandas_schema/validation.py
+++ b/pandas_schema/validation.py
@@ -364,12 +364,14 @@ class InListValidation(_SeriesValidation):
     Checks that each element in this column is contained within a list of possibilities
     """
 
-    def __init__(self, options: typing.Iterable, case_sensitive: bool = True, **kwargs):
+    def __init__(self, options: typing.Iterable, case_sensitive: bool = True, ignore_nas: bool = False, **kwargs):
         """
         :param options: A list of values to check. If the value of a cell is in this list, it is considered to pass the
             validation
+        :param ignore_nas: ignore nas (boolean, default False)
         """
         self.case_sensitive = case_sensitive
+        self.ignore_nan = ignore_nan
         self.options = options
         super().__init__(**kwargs)
 
@@ -380,9 +382,14 @@ def default_message(self):
 
     def validate(self, series: pd.Series) -> pd.Series:
         if self.case_sensitive:
-            return series.isin(self.options)
+            is_in_options = series.isin(self.options)
         else:
-            return series.str.lower().isin([s.lower() for s in self.options])
+            is_in_options = series.str.lower().isin([s.lower() for s in self.options])
+
+        if self.ignore_nas:
+            is_in_options = is_in_options | series.isna()
+
+        return is_in_options
 
 
 class DateFormatValidation(_SeriesValidation):
diff --git a/test/test_validation.py b/test/test_validation.py
index 41a0161..26af016 100644
--- a/test/test_validation.py
+++ b/test/test_validation.py
@@ -315,6 +315,44 @@ def test_invalid_elements(self):
             'accepts elements that are not in the validation list'
         )
 
+class InListIgnoringNas(ValidationTestBase):
+    def setUp(self):
+        self.validator = InListValidation(['a', 'b', 'c'], ignore_nas=True)
+
+    def test_valid_elements(self):
+        self.validate_and_compare(
+            [
+                np.NaN
+            ],
+            True,
+            'does not ignore NaNs when it should'
+        )
+
+class InListNotIgnoringNas(ValidationTestBase):
+    def setUp(self):
+        self.validator = InListValidation(['a', 'b', 'c'], ignore_nas=False)
+
+    def test_valid_elements(self):
+        self.validate_and_compare(
+            [
+                np.NaN
+            ],
+            False,
+            'ignores NaNs when it should not'
+        )
+
+class InListIgnoringNas(ValidationTestBase):
+    def setUp(self):
+        self.validator = InListValidation(['a', 'b', 'c'], ignore_nas=True)
+
+    def test_valid_elements(self):
+        self.validate_and_compare(
+            [
+                np.NaN
+            ],
+            True,
+            'does not ignore NaNs'
+        )
 
 class DateFormat(ValidationTestBase):
     def setUp(self):