diff --git a/qiskit_ibm_runtime/api/session.py b/qiskit_ibm_runtime/api/session.py
index 1a66908da..8a1bd4b7d 100644
--- a/qiskit_ibm_runtime/api/session.py
+++ b/qiskit_ibm_runtime/api/session.py
@@ -35,6 +35,7 @@
 STATUS_FORCELIST = (
     500,  # General server error
     502,  # Bad Gateway
+    503,  # Service Unavailable
     504,  # Gateway Timeout
     520,  # Cloudflare general error
     521,  # Cloudflare web server is down