The genus Pachycarpus is revised in tropical Africa and 15 species recognised in the region. Two new species (P pachyglossus and P richardsiae) and one subspecies (P grantii subsp. marroninus) are described from the southern Tanzanian highlands and two new combinations are made. Descriptions and keys to the taxa are presented and all species illustrated. In addition, a variety from southern Africa is raised to subspecific rank and the delimitation of P concolor E. Mey. expanded to include three other taxa. Asclepias browniana S. Moore, Pachycarpus robustus A. Rich., P schumannii Chiov. and Schizoglossum simulans N. E. Br. are all lectotypified and a neotype is designated for S. goetzei K. Schum.