diff --git a/open-sse/translator/request/openai-responses.js b/open-sse/translator/request/openai-responses.js
index 64740c12..ecfa26d6 100644
--- a/open-sse/translator/request/openai-responses.js
+++ b/open-sse/translator/request/openai-responses.js
@@ -380,6 +380,7 @@ export function openaiToOpenAIResponsesRequest(model, body, stream, credentials)
   if (body.top_p !== undefined) result.top_p = body.top_p;
   if (body.reasoning !== undefined) result.reasoning = body.reasoning;
   if (body.reasoning_effort !== undefined) result.reasoning = { effort: body.reasoning_effort, summary: "auto" };
+  if (body.service_tier !== undefined) result.service_tier = body.service_tier;
 
   return result;
 }