diff --git a/dist/index.js b/dist/index.js
--- a/dist/index.js
+++ b/dist/index.js
@@ -1110,6 +1110,14 @@ async function convertToXaiResponsesInput({
                   type: "input_file",
                   file_url: block.data.toString()
                 });
+              } else if (block.mediaType === "application/pdf") {
+                contentParts.push({
+                  type: "input_file",
+                  ...(typeof block.data === "string" && block.data.startsWith("file-") ? { file_id: block.data } : {
+                    filename: block.filename ?? "file",
+                    file_data: `data:application/pdf;base64,${(0, import_provider_utils5.convertToBase64)(block.data)}`
+                  })
+                });
               } else {
                 throw new import_provider4.UnsupportedFunctionalityError({
                   functionality: `file part media type ${block.mediaType} as inline data (xAI Responses requires a URL or a Files API reference for non-image files)`
diff --git a/dist/index.mjs b/dist/index.mjs
--- a/dist/index.mjs
+++ b/dist/index.mjs
@@ -1113,6 +1113,14 @@ async function convertToXaiResponsesInput({
                   type: "input_file",
                   file_url: block.data.toString()
                 });
+              } else if (block.mediaType === "application/pdf") {
+                contentParts.push({
+                  type: "input_file",
+                  ...(typeof block.data === "string" && block.data.startsWith("file-") ? { file_id: block.data } : {
+                    filename: block.filename ?? "file",
+                    file_data: `data:application/pdf;base64,${convertToBase642(block.data)}`
+                  })
+                });
               } else {
                 throw new UnsupportedFunctionalityError3({
                   functionality: `file part media type ${block.mediaType} as inline data (xAI Responses requires a URL or a Files API reference for non-image files)`
diff --git a/src/responses/convert-to-xai-responses-input.ts b/src/responses/convert-to-xai-responses-input.ts
--- a/src/responses/convert-to-xai-responses-input.ts
+++ b/src/responses/convert-to-xai-responses-input.ts
@@ -64,6 +64,17 @@ export async function convertToXaiResponsesInput({
                   type: 'input_file',
                   file_url: block.data.toString(),
                 });
+              } else if (block.mediaType === 'application/pdf') {
+                contentParts.push({
+                  type: 'input_file',
+                  ...(typeof block.data === 'string' &&
+                  block.data.startsWith('file-')
+                    ? { file_id: block.data }
+                    : {
+                        filename: block.filename ?? 'file',
+                        file_data: `data:application/pdf;base64,${convertToBase64(block.data)}`,
+                      }),
+                });
               } else {
                 throw new UnsupportedFunctionalityError({
                   functionality: `file part media type ${block.mediaType} as inline data (xAI Responses requires a URL or a Files API reference for non-image files)`,
diff --git a/src/responses/xai-responses-api.ts b/src/responses/xai-responses-api.ts
--- a/src/responses/xai-responses-api.ts
+++ b/src/responses/xai-responses-api.ts
@@ -27,6 +27,12 @@ export type XaiResponsesSystemMessage = {
 export type XaiResponsesUserMessageContentPart =
   | { type: 'input_text'; text: string }
   | { type: 'input_image'; image_url: string }
-  | { type: 'input_file'; file_url: string };
-
+  | {
+      type: 'input_file';
+      file_url?: string;
+      file_id?: string;
+      file_data?: string;
+      filename?: string;
+    };
+
 export type XaiResponsesUserMessage = {