diff --git a/src/csharp/EXPERIMENTAL-ONLY b/src/csharp/EXPERIMENTAL-ONLY
new file mode 100644
index 0000000000000000000000000000000000000000..f18a81d919e3bc02d484f35dd513787713faf896
--- /dev/null
+++ b/src/csharp/EXPERIMENTAL-ONLY
@@ -0,0 +1 @@
+gRPC C# is work-in-progress and is not intended to be used. See README.