The genus Orbea Haw. (Apocynaceae) is revised and the formerly recognized genera Orbeanthus L. C. Leach, Orbeopsis L. C. Leach, Pachycymbium L. C. Leach, and Angolluma Munster are included in it. The revision is based on a detailed survey of morphological characters and a cladistic analysis, which demonstrated lack of support for the segregate genera. The much expanded genus Orbea is the only monophyletic entity that can be recognized in this complex. One species formerly assigned to Orbea is placed in a monotypic genus, Ballyanthus, which is more closely related to Duvalia Haw. and Huernia R. Br. Orbea comprises 56 species widely distributed in Africa and the southwestern part of the Arabian peninsula; one new species, Orbea taitica, is described. Ballyanthus prognathus occurs in northern Somalia.