diff --git a/.changeset/lazy-cougars-sip.md b/.changeset/lazy-cougars-sip.md
new file mode 100644
index 000000000..7b41e0aeb
--- /dev/null
+++ b/.changeset/lazy-cougars-sip.md
@@ -0,0 +1,5 @@
+---
+"@google/generative-ai": patch
+---
+
+Added custom header support to the Server package, matching functionality on the client package
diff --git a/src/server/request.test.ts b/src/server/request.test.ts
index dd2c15d25..4a0e8299a 100644
--- a/src/server/request.test.ts
+++ b/src/server/request.test.ts
@@ -20,9 +20,17 @@ import { match, restore, stub } from "sinon";
 import * as sinonChai from "sinon-chai";
 import * as chaiAsPromised from "chai-as-promised";
 import { DEFAULT_API_VERSION, DEFAULT_BASE_URL } from "../requests/request";
-import { FilesRequestUrl, makeServerRequest } from "./request";
+import {
+  FilesRequestUrl,
+  ServerRequestUrl,
+  getHeaders,
+  makeServerRequest,
+} from "./request";
 import { RpcTask } from "./constants";
-import { GoogleGenerativeAIFetchError } from "../errors";
+import {
+  GoogleGenerativeAIFetchError,
+  GoogleGenerativeAIRequestInputError,
+} from "../errors";
 
 use(sinonChai);
 use(chaiAsPromised);
@@ -212,4 +220,24 @@ describe("Files API - request methods", () => {
       expect(fetchStub).to.be.calledOnce;
     });
   });
+  describe("getHeaders", () => {
+    it("passes custom headers", () => {
+      const url = new ServerRequestUrl(RpcTask.GET, "key", {
+        customHeaders: new Headers({ customHeader: "customHeaderValue" }),
+      });
+
+      const headers = getHeaders(url);
+
+      expect(headers.get("customHeader")).to.equal("customHeaderValue");
+    });
+    it("passes custom x-goog-api-client header", () => {
+      const url = new ServerRequestUrl(RpcTask.GET, "key", {
+        customHeaders: new Headers({ "x-goog-api-client": "client/version" }),
+      });
+
+      expect(() => getHeaders(url)).to.throw(
+        GoogleGenerativeAIRequestInputError,
+      );
+    });
+  });
 });
diff --git a/src/server/request.ts b/src/server/request.ts
index 464c1d2e2..e16de647d 100644
--- a/src/server/request.ts
+++ b/src/server/request.ts
@@ -23,6 +23,7 @@ import {
 } from "../requests/request";
 import { RequestOptions, SingleRequestOptions } from "../../types";
 import { RpcTask } from "./constants";
+import { GoogleGenerativeAIRequestInputError } from "../errors";
 
 const taskToMethod = {
   [RpcTask.UPLOAD]: "POST",
@@ -91,6 +92,35 @@ export function getHeaders(url: ServerRequestUrl): Headers {
   const headers = new Headers();
   headers.append("x-goog-api-client", getClientHeaders(url.requestOptions));
   headers.append("x-goog-api-key", url.apiKey);
+
+  let customHeaders = url.requestOptions?.customHeaders;
+  if (customHeaders) {
+    if (!(customHeaders instanceof Headers)) {
+      try {
+        customHeaders = new Headers(customHeaders);
+      } catch (e) {
+        throw new GoogleGenerativeAIRequestInputError(
+          `unable to convert customHeaders value ${JSON.stringify(
+            customHeaders,
+          )} to Headers: ${e.message}`,
+        );
+      }
+    }
+
+    for (const [headerName, headerValue] of customHeaders.entries()) {
+      if (headerName === "x-goog-api-key") {
+        throw new GoogleGenerativeAIRequestInputError(
+          `Cannot set reserved header name ${headerName}`,
+        );
+      } else if (headerName === "x-goog-api-client") {
+        throw new GoogleGenerativeAIRequestInputError(
+          `Header name ${headerName} can only be set using the apiClient field`,
+        );
+      }
+
+      headers.append(headerName, headerValue);
+    }
+  }
   return headers;
 }