diff --git a/MdePkg/Include/IndustryStandard/Pci23.h b/MdePkg/Include/IndustryStandard/Pci23.h
index 467354429e..87bd16375c 100644
--- a/MdePkg/Include/IndustryStandard/Pci23.h
+++ b/MdePkg/Include/IndustryStandard/Pci23.h
@@ -92,6 +92,7 @@
 /// PCI Capability List IDs and records.
 ///
 #define EFI_PCI_CAPABILITY_ID_PCIX    0x07
+#define EFI_PCI_CAPABILITY_ID_VENDOR  0x09
 
 #pragma pack(1)
 ///
@@ -116,6 +117,15 @@ typedef struct {
   UINT32                  SplitTransCtrlRegDn;
 } EFI_PCI_CAPABILITY_PCIX_BRDG;
 
+///
+/// Vendor Specific Capability Header
+/// Table H-1: Capability IDs, PCI Local Bus Specification, 2.3
+///
+typedef struct {
+  EFI_PCI_CAPABILITY_HDR  Hdr;
+  UINT8                   Length;
+} EFI_PCI_CAPABILITY_VENDOR_HDR;
+
 #pragma pack()
 
 #define PCI_CODE_TYPE_EFI_IMAGE       0x03