diff --git a/fio.1 b/fio.1
index b7046d5..e48a16a 100644
--- a/fio.1
+++ b/fio.1
@@ -410,6 +410,10 @@
 .br
 See <http://www.xmailserver.org/guasi\-lib.html>.
 .TP
+.B rdma
+The RDMA I/O engine supports both RDMA memory semantic(RDMA_WRITE/RDMA_READ)
+and channel semantic(Send/Recv) in InfiniBand, RoCE and iWarp environment.
+.TP
 .B external
 Loads an external I/O engine object file.  Append the engine filename as
 `:\fIenginepath\fR'.