diff --git a/openapi_core/contrib/requests/requests.py b/openapi_core/contrib/requests/requests.py
index 00a462f5..c39110cc 100644
--- a/openapi_core/contrib/requests/requests.py
+++ b/openapi_core/contrib/requests/requests.py
@@ -68,7 +68,10 @@ def body(self) -> Optional[str]:
         if self.request.body is None:
             return None
         if isinstance(self.request.body, bytes):
-            return self.request.body.decode("utf-8")
+            try:
+                return self.request.body.decode("utf-8")
+            except UnicodeDecodeError:
+                return self.request.body
         assert isinstance(self.request.body, str)
         # TODO: figure out if request._body_position is relevant
         return self.request.body
diff --git a/openapi_core/contrib/requests/responses.py b/openapi_core/contrib/requests/responses.py
index 66343802..f31e2ee5 100644
--- a/openapi_core/contrib/requests/responses.py
+++ b/openapi_core/contrib/requests/responses.py
@@ -12,7 +12,10 @@ def __init__(self, response: Response):
     @property
     def data(self) -> str:
         assert isinstance(self.response.content, bytes)
-        return self.response.content.decode("utf-8")
+        try:
+            return self.response.content.decode("utf-8")
+        except UnicodeDecodeError:
+            return self.response.content
 
     @property
     def status_code(self) -> int: