diff --git a/google/pubsub/v1/pubsub.proto b/google/pubsub/v1/pubsub.proto
index ea0d4c7e..8ee03eb1 100644
--- a/google/pubsub/v1/pubsub.proto
+++ b/google/pubsub/v1/pubsub.proto
@@ -609,6 +609,52 @@ message Subscription {
   // *default policy* with `ttl` of 31 days will be used. The minimum allowed
   // value for `expiration_policy.ttl` is 1 day.
   ExpirationPolicy expiration_policy = 11;
+
+  // A policy that specifies the conditions for dead lettering messages in
+  // this subscription. If dead_letter_policy is not set, dead lettering
+  // is disabled.
+  //
+  // The Cloud Pub/Sub service account associated with this subscriptions's
+  // parent project (i.e.,
+  // service-{project_number}@gcp-sa-pubsub.iam.gserviceaccount.com) must have
+  // permission to Acknowledge() messages on this subscription.
+  // <b>EXPERIMENTAL:</b> This feature is part of a closed alpha release. This
+  // API might be changed in backward-incompatible ways and is not recommended
+  // for production use. It is not subject to any SLA or deprecation policy.
+  DeadLetterPolicy dead_letter_policy = 13;
+}
+
+// Dead lettering is done on a best effort basis. The same message might be
+// dead lettered multiple times.
+//
+// If validation on any of the fields fails at subscription creation/updation,
+// the create/update subscription request will fail.
+message DeadLetterPolicy {
+  // The name of the topic to which dead letter messages should be published.
+  // Format is `projects/{project}/topics/{topic}`.The Cloud Pub/Sub service
+  // account associated with the enclosing subscription's parent project (i.e.,
+  // service-{project_number}@gcp-sa-pubsub.iam.gserviceaccount.com) must have
+  // permission to Publish() to this topic.
+  //
+  // The operation will fail if the topic does not exist.
+  // Users should ensure that there is a subscription attached to this topic
+  // since messages published to a topic with no subscriptions are lost.
+  string dead_letter_topic = 1;
+
+  // The maximum number of delivery attempts for any message. The value must be
+  // between 5 and 100.
+  //
+  // The number of delivery attempts is defined as 1 + (the sum of number of
+  // NACKs and number of times the acknowledgement deadline has been exceeded
+  // for the message).
+  //
+  // A NACK is any call to ModifyAckDeadline with a 0 deadline. Note that
+  // client libraries may automatically extend ack_deadlines.
+  //
+  // This field will be honored on a best effort basis.
+  //
+  // If this parameter is 0, a default value of 5 is used.
+  int32 max_delivery_attempts = 2;
 }
 
 // A policy that specifies the conditions for resource expiration (i.e.,
@@ -770,8 +816,9 @@ message PullRequest {
   // least one message is available, rather than returning no messages.
   bool return_immediately = 2;
 
-  // The maximum number of messages returned for this request. The Pub/Sub
-  // system may return fewer than the number specified.
+  // The maximum number of messages to return for this request. Must be a
+  // positive integer. The Pub/Sub system may return fewer than the number
+  // specified.
   int32 max_messages = 3;
 }