diff --git a/openapi_core/schema/schemas/models.py b/openapi_core/schema/schemas/models.py
index 11438a4..0351e1a 100644
--- a/openapi_core/schema/schemas/models.py
+++ b/openapi_core/schema/schemas/models.py
@@ -20,6 +20,7 @@ from openapi_core.schema.schemas.exceptions import (
 )
 from openapi_core.schema.schemas.util import (
     forcebool, format_date, format_datetime,
+    format_uuid,
 )
 from openapi_core.schema.schemas.validators import (
     TypeValidator, AttributeValidator,
@@ -46,7 +47,7 @@ class Schema(object):
             format_date, TypeValidator(date, exclude=datetime)),
         SchemaFormat.DATETIME: Format(format_datetime, TypeValidator(datetime)),
         SchemaFormat.BINARY: Format(binary_type, TypeValidator(binary_type)),
-        SchemaFormat.UUID: Format(UUID, TypeValidator(UUID)),
+        SchemaFormat.UUID: Format(format_uuid, TypeValidator(UUID)),
         SchemaFormat.BYTE: Format(b64decode, TypeValidator(binary_type)),
     }
 
diff --git a/openapi_core/schema/schemas/util.py b/openapi_core/schema/schemas/util.py
index 19c8b5c..7c274ec 100644
--- a/openapi_core/schema/schemas/util.py
+++ b/openapi_core/schema/schemas/util.py
@@ -4,6 +4,7 @@ from distutils.util import strtobool
 from json import dumps
 from six import string_types
 import strict_rfc3339
+from uuid import UUID
 
 
 def forcebool(val):
@@ -24,3 +25,9 @@ def format_date(value):
 def format_datetime(value):
     timestamp = strict_rfc3339.rfc3339_to_timestamp(value)
     return datetime.datetime.utcfromtimestamp(timestamp)
+
+
+def format_uuid(value):
+    if isinstance(value, UUID):
+        return value
+    return UUID(value)
diff --git a/tests/unit/schema/test_schemas.py b/tests/unit/schema/test_schemas.py
index d6799fc..f41af34 100644
--- a/tests/unit/schema/test_schemas.py
+++ b/tests/unit/schema/test_schemas.py
@@ -5,6 +5,7 @@ import mock
 import pytest
 
 from openapi_core.extensions.models.models import Model
+from openapi_core.schema.schemas.enums import SchemaFormat, SchemaType
 from openapi_core.schema.schemas.exceptions import (
     InvalidSchemaValue, MultipleOneOfSchema, NoOneOfSchema, OpenAPISchemaError,
     UndefinedSchemaProperty
@@ -49,6 +50,22 @@ class TestSchemaUnmarshal(object):
 
         assert result == value
 
+    def test_string_format_uuid_valid(self):
+        schema = Schema(SchemaType.STRING, schema_format=SchemaFormat.UUID)
+        value = str(uuid.uuid4())
+
+        result = schema.unmarshal(value)
+
+        assert result == uuid.UUID(value)
+
+    def test_string_format_uuid_uuid_quirks_valid(self):
+        schema = Schema(SchemaType.STRING, schema_format=SchemaFormat.UUID)
+        value = uuid.uuid4()
+
+        result = schema.unmarshal(value, strict=False)
+
+        assert result == value
+
     def test_string_float_invalid(self):
         schema = Schema('string')
         value = 1.23