diff --git a/.changeset/nine-otters-change.md b/.changeset/nine-otters-change.md
new file mode 100644
index 000000000..4ad92bd4d
--- /dev/null
+++ b/.changeset/nine-otters-change.md
@@ -0,0 +1,5 @@
+---
+"@azure-tools/cadl-ranch-specs": patch
+---
+
+Add test for `@include` over `@internal`
diff --git a/packages/cadl-ranch-specs/cadl-ranch-summary.md b/packages/cadl-ranch-specs/cadl-ranch-summary.md
index d730d4eef..232fd87ef 100644
--- a/packages/cadl-ranch-specs/cadl-ranch-summary.md
+++ b/packages/cadl-ranch-specs/cadl-ranch-summary.md
@@ -85,6 +85,24 @@ Expected response body:
 }
 ```
 
+### Azure_ClientGenerator_Core_Internal_internalWithIncludeModel
+
+- Endpoint: `post /azure/client-generator-core/internal/internal`
+
+This scenario contains an internal operation. It should be generated but not exposed.
+Expected body parameter:
+
+````json
+{
+  "name": <any string>
+}
+Expected response body:
+```json
+{
+  "name": <any string>
+}
+````
+
 ### Azure_ClientGenerator_Core_Internal_publicOnly
 
 - Endpoint: `get /azure/client-generator-core/internal/public`
diff --git a/packages/cadl-ranch-specs/http/azure/client-generator-core/internal/main.tsp b/packages/cadl-ranch-specs/http/azure/client-generator-core/internal/main.tsp
index 3f85b928e..c313d7b56 100644
--- a/packages/cadl-ranch-specs/http/azure/client-generator-core/internal/main.tsp
+++ b/packages/cadl-ranch-specs/http/azure/client-generator-core/internal/main.tsp
@@ -20,6 +20,18 @@ model InternalModel {
   name: string;
 }
 
+@doc("This is a model only used by internal operation. Also, it is decorated with @include. It should be generated and exported.")
+@global.Azure.ClientGenerator.Core.include
+model InternalIncludeModel {
+  name: string;
+  nested: NestedIncludeModel;
+}
+
+@doc("This is a model referred by model decorated with @include. It should be generated and exported.")
+model NestedIncludeModel {
+  comment: string;
+}
+
 @doc("This is a model used by both public and internal operation. It should be generated and exported.")
 model SharedModel {
   name: string;
@@ -56,6 +68,26 @@ Expected response body:
 @global.Azure.ClientGenerator.Core.internal
 op internalOnly(@query name: string): InternalModel;
 
+@scenario
+@scenarioDoc("""
+This scenario contains an internal operation. It should be generated but not exposed.
+Expected body parameter:
+```json
+{
+  "name": <any string>
+}
+Expected response body:
+```json
+{
+  "name": <any string>
+}
+```
+""")
+@route("/internal")
+@post
+@global.Azure.ClientGenerator.Core.internal
+op internalWithIncludeModel(@body body: InternalIncludeModel): InternalIncludeModel;
+
 @route("/shared")
 @global.Azure.ClientGenerator.Core.operationGroup
 @scenario
diff --git a/packages/cadl-ranch-specs/http/azure/client-generator-core/internal/mockapi.ts b/packages/cadl-ranch-specs/http/azure/client-generator-core/internal/mockapi.ts
index 7d6ceefa7..d4af07df8 100644
--- a/packages/cadl-ranch-specs/http/azure/client-generator-core/internal/mockapi.ts
+++ b/packages/cadl-ranch-specs/http/azure/client-generator-core/internal/mockapi.ts
@@ -3,7 +3,7 @@ import { ScenarioMockApi } from "@azure-tools/cadl-ranch-api";
 
 export const Scenarios: Record<string, ScenarioMockApi> = {};
 
-function createInternalMockApis(route: string): MockApi {
+function createInternalGetMockApis(route: string): MockApi {
   const url = `/azure/client-generator-core/internal/${route}`;
   return mockapi.get(url, (req) => {
     if (!("name" in req.query)) {
@@ -16,9 +16,19 @@ function createInternalMockApis(route: string): MockApi {
   });
 }
 
-Scenarios.Azure_ClientGenerator_Core_Internal_publicOnly = passOnSuccess(createInternalMockApis("public"));
-Scenarios.Azure_ClientGenerator_Core_Internal_internalOnly = passOnSuccess(createInternalMockApis("internal"));
+Scenarios.Azure_ClientGenerator_Core_Internal_publicOnly = passOnSuccess(createInternalGetMockApis("public"));
+Scenarios.Azure_ClientGenerator_Core_Internal_internalOnly = passOnSuccess(createInternalGetMockApis("internal"));
 Scenarios.Azure_ClientGenerator_Core_Internal_Shared = passOnSuccess([
-  createInternalMockApis("shared/public"),
-  createInternalMockApis("shared/internal"),
+  createInternalGetMockApis("shared/public"),
+  createInternalGetMockApis("shared/internal"),
 ]);
+
+Scenarios.Azure_ClientGenerator_Core_Internal_internalWithIncludeModel = passOnSuccess(
+  mockapi.post("/azure/client-generator-core/internal/internal", (req) => {
+    req.expect.bodyNotEmpty();
+    return {
+      status: 200,
+      body: json({ name: req.body["name"] }),
+    };
+  }),
+);