diff --git a/ceilometer/api/controllers/v2.py b/ceilometer/api/controllers/v2.py
index d52b12d71..57600bc75 100644
--- a/ceilometer/api/controllers/v2.py
+++ b/ceilometer/api/controllers/v2.py
@@ -1053,6 +1053,11 @@ class ValidatedComplexQuery(object):
         "minProperties": 1,
         "maxProperties": 1}
 
+    schema_value_in = {
+        "type": "array",
+        "items": {"oneOf": [{"type": "string"},
+                            {"type": "number"}]}}
+
     schema_field = {
         "type": "object",
         "patternProperties": {"[\S]+": schema_value},
@@ -1060,6 +1065,13 @@ class ValidatedComplexQuery(object):
         "minProperties": 1,
         "maxProperties": 1}
 
+    schema_field_in = {
+        "type": "object",
+        "patternProperties": {"[\S]+": schema_value_in},
+        "additionalProperties": False,
+        "minProperties": 1,
+        "maxProperties": 1}
+
     schema_leaf = {
         "type": "object",
         "patternProperties": {simple_ops: schema_field},
@@ -1067,6 +1079,20 @@ class ValidatedComplexQuery(object):
         "minProperties": 1,
         "maxProperties": 1}
 
+    schema_leaf_in = {
+        "type": "object",
+        "patternProperties": {"(?i)^in$": schema_field_in},
+        "additionalProperties": False,
+        "minProperties": 1,
+        "maxProperties": 1}
+
+    schema_leaf_simple_ops = {
+        "type": "object",
+        "patternProperties": {simple_ops: schema_field},
+        "additionalProperties": False,
+        "minProperties": 1,
+        "maxProperties": 1}
+
     schema_and_or_array = {
         "type": "array",
         "items": {"$ref": "#"},
@@ -1080,11 +1106,13 @@ class ValidatedComplexQuery(object):
         "maxProperties": 1}
 
     schema = {
-        "oneOf": [{"$ref": "#/definitions/leaf"},
+        "oneOf": [{"$ref": "#/definitions/leaf_simple_ops"},
+                  {"$ref": "#/definitions/leaf_in"},
                   {"$ref": "#/definitions/and_or"}],
         "minProperties": 1,
         "maxProperties": 1,
-        "definitions": {"leaf": schema_leaf,
+        "definitions": {"leaf_simple_ops": schema_leaf_simple_ops,
+                        "leaf_in": schema_leaf_in,
                         "and_or": schema_and_or}}
 
     orderby_schema = {
@@ -1112,6 +1140,9 @@ class ValidatedComplexQuery(object):
         self.schema_field["patternProperties"] = {
             valid_fields: self.schema_value}
 
+        self.schema_field_in["patternProperties"] = {
+            valid_fields: self.schema_value_in}
+
         self.orderby_schema["items"]["patternProperties"] = {
             valid_fields: {"type": "string",
                            "pattern": self.order_directions}}
diff --git a/ceilometer/storage/impl_mongodb.py b/ceilometer/storage/impl_mongodb.py
index 49a10fe52..83abe40f1 100644
--- a/ceilometer/storage/impl_mongodb.py
+++ b/ceilometer/storage/impl_mongodb.py
@@ -255,7 +255,8 @@ class Connection(pymongo_base.Connection):
                  "=<": "$lte",
                  ">=": "$gte",
                  "=>": "$gte",
-                 "!=": "$ne"}
+                 "!=": "$ne",
+                 "in": "$in"}
     complex_operators = {"or": "$or",
                          "and": "$and"}
 
diff --git a/ceilometer/storage/impl_sqlalchemy.py b/ceilometer/storage/impl_sqlalchemy.py
index d44da0a70..dde99b345 100644
--- a/ceilometer/storage/impl_sqlalchemy.py
+++ b/ceilometer/storage/impl_sqlalchemy.py
@@ -180,6 +180,10 @@ def make_query_from_filter(session, query, sample_filter, require_meter=True):
     return query
 
 
+def operator_in(field_name, field_value):
+    return field_name.in_(field_value)
+
+
 class Connection(base.Connection):
     """SqlAlchemy connection."""
 
@@ -190,7 +194,8 @@ class Connection(base.Connection):
                  "=<": operator.le,
                  ">=": operator.ge,
                  "=>": operator.ge,
-                 "!=": operator.ne}
+                 "!=": operator.ne,
+                 "in": operator_in}
     complex_operators = {"or": or_,
                          "and": and_}
     ordering_functions = {"asc": asc,
diff --git a/ceilometer/tests/api/v2/test_complex_query.py b/ceilometer/tests/api/v2/test_complex_query.py
index 4c72c6f69..70d69d67c 100644
--- a/ceilometer/tests/api/v2/test_complex_query.py
+++ b/ceilometer/tests/api/v2/test_complex_query.py
@@ -300,6 +300,14 @@ class TestFilterSyntaxValidation(test.BaseTestCase):
                          {"=": {"counter_name": "value"}}]}
         self.query._validate_filter(filter)
 
+    def test_complex_operator_with_in(self):
+        filter = {"and": [{"<": {"counter_volume": 42}},
+                          {">=": {"counter_volume": 36}},
+                          {"in": {"project_id": ["project_id1",
+                                                 "project_id2",
+                                                 "project_id3"]}}]}
+        self.query._validate_filter(filter)
+
     def test_invalid_complex_operator(self):
         filter = {"xor": [{"=": {"project_id": "string_value"}},
                           {"=": {"resource_id": "value"}}]}
diff --git a/ceilometer/tests/api/v2/test_complex_query_scenarios.py b/ceilometer/tests/api/v2/test_complex_query_scenarios.py
index 8f9aff293..16f2d2d3c 100644
--- a/ceilometer/tests/api/v2/test_complex_query_scenarios.py
+++ b/ceilometer/tests/api/v2/test_complex_query_scenarios.py
@@ -153,6 +153,18 @@ class TestQueryMetersController(tests_api.FunctionalTest,
             self.assertIn(sample['project_id'],
                           (["project-id1", "project-id2"]))
 
+    def test_admin_tenant_sees_every_project_with_in_filter(self):
+        filter = ('{"In": ' +
+                  '{"project_id": ["project-id1", "project-id2"]}}')
+        data = self.post_json(self.url,
+                              params={"filter": filter},
+                              headers=admin_header)
+
+        self.assertEqual(2, len(data.json))
+        for sample in data.json:
+            self.assertIn(sample['project_id'],
+                          (["project-id1", "project-id2"]))
+
     def test_admin_tenant_can_query_any_project(self):
         data = self.post_json(self.url,
                               params={"filter":
diff --git a/ceilometer/tests/storage/test_storage_scenarios.py b/ceilometer/tests/storage/test_storage_scenarios.py
index d7a99613a..566106ab6 100644
--- a/ceilometer/tests/storage/test_storage_scenarios.py
+++ b/ceilometer/tests/storage/test_storage_scenarios.py
@@ -747,6 +747,14 @@ class ComplexSampleQueryTest(DBTestBase,
                                      {"and":
                                       [{"=": {"counter_name": "cpu_util"}},
                                        {"and": and_expression}]}]}
+        in_expression = {"in": {"resource_id": ["resource-id-42",
+                                                "resource-id-43",
+                                                "resource-id-44"]}}
+        self.complex_filter_in = {"and":
+                                  [in_expression,
+                                   {"and":
+                                    [{"=": {"counter_name": "cpu_util"}},
+                                     {"and": and_expression}]}]}
 
     def _create_samples(self):
         for resource in range(42, 45):
@@ -900,6 +908,26 @@ class ComplexSampleQueryTest(DBTestBase,
                                                      orderby=orderby))
         self.assertRaises(KeyError, query)
 
+    def test_query_complex_filter_with_in(self):
+        self._create_samples()
+        results = list(
+            self.conn.query_samples(filter_expr=self.complex_filter_in))
+        self.assertEqual(len(results), 9)
+        for sample in results:
+            self.assertIn(sample.resource_id,
+                          set(["resource-id-42",
+                               "resource-id-43",
+                               "resource-id-44"]))
+            self.assertEqual(sample.counter_name,
+                             "cpu_util")
+            self.assertTrue(sample.counter_volume > 0.4)
+            self.assertTrue(sample.counter_volume <= 0.8)
+
+    def test_query_filter_with_empty_in(self):
+        results = list(
+            self.conn.query_samples(filter_expr={"in": {"resource_id": []}}))
+        self.assertEqual(len(results), 0)
+
 
 class StatisticsTest(DBTestBase,
                      tests_db.MixinTestsWithBackendScenarios):
diff --git a/doc/source/webapi/v2.rst b/doc/source/webapi/v2.rst
index 38784b832..440c60204 100644
--- a/doc/source/webapi/v2.rst
+++ b/doc/source/webapi/v2.rst
@@ -95,7 +95,7 @@ Complex Query
 +++++++++++++
 The filter expressions of the Complex Query feature operate on the fields
 of *Sample*, *Alarm* and *AlarmChange*. The following comparison operators are
-supported: *=*, *!=*, *<*, *<=*, *>* and *>=*; and the following logical
+supported: *=*, *!=*, *<*, *<=*, *>*, *>=* and *in*; and the following logical
 operators can be used: *and* and *or*. The field names are validated against
 the database models.