diff --git a/MdePkg/Include/IndustryStandard/Http11.h b/MdePkg/Include/IndustryStandard/Http11.h
index 8a09f96010..ace335a376 100644
--- a/MdePkg/Include/IndustryStandard/Http11.h
+++ b/MdePkg/Include/IndustryStandard/Http11.h
@@ -235,6 +235,20 @@
 ///
 #define  HTTP_HEADER_X_AUTH_TOKEN      "X-Auth-Token"
 
+///
+/// Expect Header
+/// The "Expect" header field in a request indicates a certain set of
+/// behaviors (expectations) that need to be supported by the server in
+/// order to properly handle this request. The only such expectation
+/// defined by this specification is 100-continue.
+///
+#define  HTTP_HEADER_EXPECT            "Expect"
+
+///
+/// Expect Header Value
+///
+#define  HTTP_EXPECT_100_CONTINUE       "100-continue"
+
 #pragma pack()
 
 #endif