A comprehensive taxonomic revision of the genus Mitrephora (Annonaceae) in Cambodia (Kampuchea), Laos, and Vietnam is presented. Eight species are recognized, including five that are newly described, viz. M. calcarea sp. nov., M. macclurei sp. nov., M. pallens, M. petelotii sp. nov., M. phanrangensis sp. nov., M. poilanei sp. nov., M. teysmannii, and M. tomentosa (inclusive of M. thorelii). Previous taxonomic confusion regarding the delimitation of M. calcarea is clarified and the name is validated for the first time. The correct application of the name M. maingayi is clarified: although the name has been used to refer to a species that is distinct within the region, the name itself is a synonym of M. teysmannii. Most of the Indochinese collections determined as “M. maingayi” are shown here to represent a new species, M. macclurei.