We present here a taxonomic study of Apocynaceae from the Atlantic Forest remnants in the state of Rio Grande do Norte (RN), Northeast Brazil. Twenty-four species in 18 genera, distributed in Apocynoid grade (3 genera/5 species), Asclepiadoideae (8 genera/10 spp.), and Rauvolfioid grade (7 genera/9 spp.) were recorded. The most species-rich genera were Aspidosperma, Ditassa, and Mandevilla with three species each. The other genera were represented by one species each. Five genera and seven species were recorded in Rio Grande do Norte for the first time. Descriptions, identification key and comments on distribution and taxonomy of both genera and species are presented, as well as illustrations and figures.