Ssmmary.A new machairodont,Therailurus piveteaui, is described.The specimens from Sterkfontein described by Broom (1937) asMegantereon barlowiare discussed, and it is concluded that reference to the genusMeganttreonis incorrect. A new specimen from the same deposit appears to belong to the same species as Broom's specimens and shows many similarities toTherailurus piveteaui.It is concluded that all belong to a second species ofTherailurus, which thus becomesTherailurus barlowi(Broom). On the basis of the new material an amplified description ofTherailurus barlowiis given.A mandibular fragment from Swartkrans is described. Its similarities toT. piveteauiandT. barlowiindicate that it represents another species of the same genus.A new species ofMegantereon, M. eurynodon, from the Kromdraai deposit is described.Two incompletely identified mandibular fragments from the Swartkrans deposit are described: of these one is referred to the Nimravidae, and the other to the Machairodontinae. The latter may possibly be a species ofMegantereon.Fragmentary lower carnassials from Kromdraai are also described: these may possibly belong to a species ofEpimachairodus.A list of all the known fossil machairodonts from the Transvaal deposits is given, and the implications as to the dating of the deposits are discussed. It is concluded that the material does not provide any basis for an accurate dating of the deposits, but supports the view that they are not all strictly contemporaneous. The affinities of the fauna are considered to be with South East Asia, rather than Europe.