The genus Cyathostemma Griff., occurring from SW China to NE Australia, is revised, and a total of ten species is recognised. One new species, C. siamensis, is described. The status of the genus Tetrapetalum Miq. is discussed and reduced, in part, to synonymy with Cyathostemma, and in part to Uvaria L. A key to taxa is given, with new descriptions and distribution maps.