diff --git a/quic/core/quic_connection.cc b/quic/core/quic_connection.cc
index 81fab03..2fe7af3 100644
--- a/quic/core/quic_connection.cc
+++ b/quic/core/quic_connection.cc
@@ -640,7 +640,6 @@
   // 2) Client side's rollout can be protected by the same connection option.
   connection_migration_use_new_cid_ =
       validate_client_addresses_ &&
-      GetQuicReloadableFlag(quic_drop_unsent_path_response) &&
       GetQuicReloadableFlag(quic_connection_migration_use_new_cid_v2);
   if (config.HasReceivedMaxPacketSize()) {
     peer_max_packet_size_ = config.ReceivedMaxPacketSize();
@@ -1741,19 +1740,10 @@
   // Queue or send PATH_RESPONSE. Send PATH_RESPONSE to the source address of
   // the current incoming packet, even if it's not the default path or the
   // alternative path.
-  const bool success = SendPathResponse(
-      frame.data_buffer, last_received_packet_info_.source_address,
-      current_effective_peer_address);
-  if (GetQuicReloadableFlag(quic_drop_unsent_path_response)) {
-    QUIC_RELOADABLE_FLAG_COUNT(quic_drop_unsent_path_response);
-  }
-  if (!success) {
+  if (!SendPathResponse(frame.data_buffer,
+                        last_received_packet_info_.source_address,
+                        current_effective_peer_address)) {
     QUIC_CODE_COUNT(quic_failed_to_send_path_response);
-    if (!GetQuicReloadableFlag(quic_drop_unsent_path_response)) {
-      // Queue the payloads to re-try later.
-      pending_path_challenge_payloads_.push_back(
-          {frame.data_buffer, last_received_packet_info_.source_address});
-    }
   }
   // TODO(b/150095588): change the stats to
   // num_valid_path_challenge_received.
@@ -2869,23 +2859,6 @@
     }
   }
 
-  // TODO(danzh) PATH_RESPONSE is of more interest to the peer than ACK,
-  // evaluate if it's worth to send them before sending ACKs.
-  while (!pending_path_challenge_payloads_.empty()) {
-    QUIC_RELOADABLE_FLAG_COUNT_N(quic_send_path_response2, 4, 5);
-    const PendingPathChallenge& pending_path_challenge =
-        pending_path_challenge_payloads_.front();
-    // Note connection_migration_use_cid_ will depends on
-    // quic_drop_unsent_path_response flag eventually, and hence the empty
-    // effective_peer_address here will not be used.
-    if (!SendPathResponse(pending_path_challenge.received_path_challenge,
-                          pending_path_challenge.peer_address,
-                          /*effective_peer_address=*/QuicSocketAddress())) {
-      break;
-    }
-    pending_path_challenge_payloads_.pop_front();
-  }
-
   // Sending queued packets may have caused the socket to become write blocked,
   // or the congestion manager to prohibit sending.
   if (!CanWrite(HAS_RETRANSMITTABLE_DATA)) {
diff --git a/quic/core/quic_connection.h b/quic/core/quic_connection.h
index a545527..954eb6a 100644
--- a/quic/core/quic_connection.h
+++ b/quic/core/quic_connection.h
@@ -2169,13 +2169,6 @@
   quiche::QuicheCircularDeque<QuicPathFrameBuffer>
       received_path_challenge_payloads_;
 
-  // Buffer outstanding PATH_CHALLENGEs if socket write is blocked, future
-  // OnCanWrite will attempt to respond with PATH_RESPONSEs using the retained
-  // payload and peer addresses.
-  // TODO(fayang): remove this when deprecating quic_drop_unsent_path_response.
-  quiche::QuicheCircularDeque<PendingPathChallenge>
-      pending_path_challenge_payloads_;
-
   // When we receive a RETRY packet or some INITIAL packets, we replace
   // |server_connection_id_| with the value from that packet and save off the
   // original value of |server_connection_id_| into
diff --git a/quic/core/quic_connection_test.cc b/quic/core/quic_connection_test.cc
index 98978e9..fba066c 100644
--- a/quic/core/quic_connection_test.cc
+++ b/quic/core/quic_connection_test.cc
@@ -12528,30 +12528,6 @@
   writer_->SetWriteBlocked();
   ProcessFramesPacketWithAddresses(frames, kSelfAddress, kNewPeerAddress,
                                    ENCRYPTION_FORWARD_SECURE);
-
-  if (GetQuicReloadableFlag(quic_drop_unsent_path_response)) {
-    EXPECT_EQ(0u, QuicConnectionPeer::NumPendingPathChallengesToResponse(
-                      &connection_));
-    return;
-  }
-  ASSERT_EQ(
-      1u, QuicConnectionPeer::NumPendingPathChallengesToResponse(&connection_));
-
-  EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(AtLeast(1));
-  writer_->SetWritable();
-  connection_.OnCanWrite();
-  EXPECT_EQ(1u, writer_->path_response_frames().size());
-  // The final check is to ensure that the random data in the response
-  // matches the random data from the challenge.
-  EXPECT_EQ(0, memcmp(path_frame_buffer.data(),
-                      &(writer_->path_response_frames().front().data_buffer),
-                      sizeof(path_frame_buffer)));
-  EXPECT_EQ(1u, writer_->padding_frames().size());
-  // PATH_RESPONSE should be sent in another packet to a different peer
-  // address.
-  EXPECT_EQ(kNewPeerAddress, writer_->last_write_peer_address());
-  EXPECT_EQ(
-      0u, QuicConnectionPeer::NumPendingPathChallengesToResponse(&connection_));
 }
 
 // Regression test for b/168101557.
diff --git a/quic/core/quic_flags_list.h b/quic/core/quic_flags_list.h
index d955f5d..fd29e1f 100644
--- a/quic/core/quic_flags_list.h
+++ b/quic/core/quic_flags_list.h
@@ -73,8 +73,6 @@
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_count_bytes_on_alternative_path_seperately, true)
 // If true, do not use the gQUIC common certificate set for certificate compression.
 QUIC_FLAG(FLAGS_quic_restart_flag_quic_no_common_cert_set, true)
-// If true, drop unsent PATH_RESPONSEs and rely on peer\'s retry.
-QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_drop_unsent_path_response, true)
 // If true, enable server retransmittable on wire PING.
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_enable_server_on_wire_ping, true)
 // If true, flush pending frames as well as pending padding bytes on connection migration.
diff --git a/quic/test_tools/quic_connection_peer.cc b/quic/test_tools/quic_connection_peer.cc
index ec579be..207582f 100644
--- a/quic/test_tools/quic_connection_peer.cc
+++ b/quic/test_tools/quic_connection_peer.cc
@@ -413,12 +413,6 @@
   return connection->undecryptable_packets_.size();
 }
 
-// static
-size_t QuicConnectionPeer::NumPendingPathChallengesToResponse(
-    QuicConnection* connection) {
-  return connection->pending_path_challenge_payloads_.size();
-}
-
 void QuicConnectionPeer::SetConnectionClose(QuicConnection* connection) {
   connection->connected_ = false;
 }
diff --git a/quic/test_tools/quic_connection_peer.h b/quic/test_tools/quic_connection_peer.h
index 26d2f41..62ed60e 100644
--- a/quic/test_tools/quic_connection_peer.h
+++ b/quic/test_tools/quic_connection_peer.h
@@ -168,8 +168,6 @@
 
   static size_t NumUndecryptablePackets(QuicConnection* connection);
 
-  static size_t NumPendingPathChallengesToResponse(QuicConnection* connection);
-
   static void SetConnectionClose(QuicConnection* connection);
 
   static void SendPing(QuicConnection* connection);