diff --git a/fastapi/openapi/utils.py b/fastapi/openapi/utils.py
index 808646cc2..eb6b29190 100644
--- a/fastapi/openapi/utils.py
+++ b/fastapi/openapi/utils.py
@@ -263,6 +263,7 @@ def get_openapi_path(
     separate_input_output_schemas: bool = True,
 ) -> Tuple[Dict[str, Any], Dict[str, Any], Dict[str, Any]]:
     path = {}
+    empty_responses: List[str] = []
     security_schemes: Dict[str, Any] = {}
     definitions: Dict[str, Any] = {}
     assert route.methods is not None, "Methods must be a list"
@@ -378,7 +379,7 @@ def get_openapi_path(
                     additional_response,
                 ) in route.responses.items():
                     process_response = additional_response.copy()
-                    process_response.pop("model", None)
+                    process_response_model = process_response.pop("model", None)
                     status_code_key = str(additional_status_code).upper()
                     if status_code_key == "DEFAULT":
                         status_code_key = "default"
@@ -388,6 +389,8 @@ def get_openapi_path(
                     assert isinstance(process_response, dict), (
                         "An additional response must be a dict"
                     )
+                    if not process_response and not process_response_model:
+                        empty_responses.append(str(additional_status_code))
                     field = route.response_fields.get(additional_status_code)
                     additional_field_schema: Optional[Dict[str, Any]] = None
                     if field:
@@ -439,6 +442,9 @@ def get_openapi_path(
                     )
             if route.openapi_extra:
                 deep_dict_update(operation, route.openapi_extra)
+            if empty_responses:
+                for response_status_code in empty_responses:
+                    del operation["responses"][response_status_code]
             path[method.lower()] = operation
     return path, security_schemes, definitions
 
diff --git a/tests/test_additional_response_empty.py b/tests/test_additional_response_empty.py
new file mode 100644
index 000000000..628386cbd
--- /dev/null
+++ b/tests/test_additional_response_empty.py
@@ -0,0 +1,69 @@
+from typing import Dict
+
+from fastapi import FastAPI
+from fastapi.testclient import TestClient
+from pydantic import BaseModel
+
+app = FastAPI()
+
+
+class Items(BaseModel):
+    items: Dict[str, int]
+
+
+@app.post("/foo", responses={422: {}})
+def foo(items: Items):
+    pass  # pragma: no cover
+
+
+client = TestClient(app)
+
+
+openapi_schema = {
+    "openapi": "3.1.0",
+    "info": {"title": "FastAPI", "version": "0.1.0"},
+    "paths": {
+        "/foo": {
+            "post": {
+                "summary": "Foo",
+                "operationId": "foo_foo_post",
+                "requestBody": {
+                    "content": {
+                        "application/json": {
+                            "schema": {"$ref": "#/components/schemas/Items"}
+                        }
+                    },
+                    "required": True,
+                },
+                "responses": {
+                    "200": {
+                        "description": "Successful Response",
+                        "content": {"application/json": {"schema": {}}},
+                    }
+                },
+            }
+        }
+    },
+    "components": {
+        "schemas": {
+            "Items": {
+                "title": "Items",
+                "required": ["items"],
+                "type": "object",
+                "properties": {
+                    "items": {
+                        "title": "Items",
+                        "type": "object",
+                        "additionalProperties": {"type": "integer"},
+                    }
+                },
+            }
+        }
+    },
+}
+
+
+def test_additional_properties_schema():
+    response = client.get("/openapi.json")
+    assert response.status_code == 200, response.text
+    assert response.json() == openapi_schema