diff --git a/.changeset/fix-openapi-type-only-schema-import.md b/.changeset/fix-openapi-type-only-schema-import.md
new file mode 100644
index 00000000000..db68e671eaf
--- /dev/null
+++ b/.changeset/fix-openapi-type-only-schema-import.md
@@ -0,0 +1,5 @@
+---
+"@effect/openapi-generator": patch
+---
+
+Fix missing Schema imports in generated type-only HTTP clients with open object schemas.
diff --git a/packages/tools/openapi-generator/src/JsonSchemaGenerator.ts b/packages/tools/openapi-generator/src/JsonSchemaGenerator.ts
index 2f2bbf05819..febf93181e3 100644
--- a/packages/tools/openapi-generator/src/JsonSchemaGenerator.ts
+++ b/packages/tools/openapi-generator/src/JsonSchemaGenerator.ts
@@ -128,11 +128,14 @@ function makeWithRepresentation() {
       renderSchemaTypeAndRuntime(name, generated.codeDocument.codes[i], typeOnly, options)
     )
 
-    return renderImportArtifacts(generated.codeDocument, !typeOnly) +
-      render("recursive declarations", recursiveDeclarations) +
+    const declarations = render("recursive declarations", recursiveDeclarations) +
       render("non-recursive definitions", nonRecursives) +
       render("recursive definitions", recursives) +
       render("schemas", codes)
+    const schemaImport = typeOnly && referencesSchema(declarations)
+      ? "import type * as Schema from \"effect/Schema\"\n"
+      : ""
+    return renderImportArtifacts(generated.codeDocument, !typeOnly) + schemaImport + declarations
   }
 
   function generateHttpApi(
@@ -343,6 +346,11 @@ function render(title: string, as: ReadonlyArray<string>) {
   return "// " + title + "\n" + as.join("\n") + "\n"
 }
 
+// Quoted property names and literal types can contain "Schema." without referencing the namespace.
+function referencesSchema(declarations: string): boolean {
+  return /\bSchema\./.test(declarations.replace(/"(?:\\.|[^"\\])*"/g, ""))
+}
+
 function renderImportArtifacts(codeDocument: SchemaRepresentation.CodeDocument, enabled: boolean): string {
   if (!enabled) return ""
   const imports = codeDocument.artifacts.flatMap((artifact) =>
diff --git a/packages/tools/openapi-generator/test/OpenApiGenerator.test.ts b/packages/tools/openapi-generator/test/OpenApiGenerator.test.ts
index 4410d32be71..26d85e343e7 100644
--- a/packages/tools/openapi-generator/test/OpenApiGenerator.test.ts
+++ b/packages/tools/openapi-generator/test/OpenApiGenerator.test.ts
@@ -38,6 +38,8 @@ const assertTypeOnly = Effect.fnUntraced(function*(spec: OpenAPISpec, expected:
   })
 
   // console.log(result)
+  const failures = yield* typeCheckCases([{ sources: [result], exactOptionalPropertyTypes: true }], true)
+  assert.deepStrictEqual(failures, [[]])
   assert.strictEqual(result, expected)
 }, Effect.provide(OpenApiGenerator.layerTransformerTs))
 
@@ -148,7 +150,8 @@ const parseDiagnostics = (output: string) => {
 // which cases are clean; each of its cases is then checked on its own.
 const typeCheckCases = Effect.fnUntraced(
   function*(
-    cases: ReadonlyArray<{ readonly sources: ReadonlyArray<string>; readonly exactOptionalPropertyTypes: boolean }>
+    cases: ReadonlyArray<{ readonly sources: ReadonlyArray<string>; readonly exactOptionalPropertyTypes: boolean }>,
+    noUnusedLocals = false
   ) {
     const directory = mkdtempSync(join(dirname(fileURLToPath(import.meta.url)), ".generated-clients-"))
     return yield* Effect.gen(function*() {
@@ -171,6 +174,7 @@ const typeCheckCases = Effect.fnUntraced(
               lib: ["ESNext", "DOM"],
               module: "NodeNext",
               noEmit: true,
+              noUnusedLocals,
               skipLibCheck: true,
               strict: true,
               target: "ES2022",
@@ -1376,11 +1380,12 @@ export const TestClientError = <Tag extends string, E>(
                             id: {
                               type: "string"
                             },
-                            name: {
-                              type: "string"
+                            "Schema.property": {
+                              type: "string",
+                              enum: ["Schema.Json"]
                             }
                           },
-                          required: ["id", "name"],
+                          required: ["id", "Schema.property"],
                           additionalProperties: false
                         }
                       }
@@ -1406,7 +1411,7 @@ import * as HttpClientError from "effect/http/HttpClientError"
 import * as HttpClientRequest from "effect/http/HttpClientRequest"
 import * as HttpClientResponse from "effect/http/HttpClientResponse"
 // schemas
-export type GetUser200 = { readonly "id": string, readonly "name": string }
+export type GetUser200 = { readonly "id": string, readonly "Schema.property": "Schema.Json" }
 
 export interface OperationConfig {
   /**
@@ -1574,7 +1579,7 @@ export const TestClientError = <Tag extends string, E>(
     response,
     request: response.request,
   }) as any`
-      ))
+      ), compilationTimeout)
 
     it.effect("preserves response variants and routes binary and bodiless statuses", () =>
       assertTypeOnlyIncludes(responseMatchingSpec, [
@@ -3858,6 +3863,41 @@ export const withoutLocale = client.getGreeting({ params: {} })
         }
       ]))
 
+    itGeneratedClientsCompile("emits compilable type-only clients with implicit additional properties", {
+      openapi: "3.1.0",
+      info: { title: "Open object API", version: "1.0.0" },
+      paths: {
+        "/users": {
+          get: {
+            operationId: "getUser",
+            parameters: [],
+            responses: {
+              "200": {
+                description: "OK",
+                content: {
+                  "application/json": { schema: { $ref: "#/components/schemas/User" } }
+                }
+              }
+            },
+            tags: ["Users"],
+            security: []
+          }
+        }
+      },
+      components: {
+        schemas: {
+          User: {
+            type: "object",
+            properties: { Name: { type: "string" } },
+            required: ["Name"]
+          }
+        },
+        securitySchemes: {}
+      },
+      security: [],
+      tags: []
+    }, { formats: ["httpclient-type-only"] })
+
     itGeneratedClientsCompile("emits compilable open objects with optional properties", {
       openapi: "3.1.0",
       info: {