A 100 Mbps Ethernet standard specified to run over four pairs of category 3 UTP wires (also known as 100Base-VG, "VG" meaning voice grade). It is also called 100VG-AnyLAN because it was defined to carry both Ethernet and Token Ring frame types.

100BaseT4 was originally proposed by Hewlett-Packard, ratified by the ISO in 1995 and practically extinct by 1998.

100BaseT4 started in the IEEE 802.3u committee as Fast Ethernet. One faction wanted to keep CSMA/CD in order to keep it pure Ethernet, even though the collision domain problem limited the distances to one tenth that of 10BaseT. Another faction wanted to change to a polling architecture from the hub, called "demand priority" in order to maintain the 10BaseT distances, and also to make it a deterministic protocol.  The IEEE 802.12 committee was formed and standardized 100BaseT4.