While revising the genus Cosmostigma for the Flora of Thailand it became clear that Cosmostigma cordatum, based on Periploca cordata, is a synonym of Pentatropis capensis. Consequently, Cosmostigma racemosum is the name to be used for the only species of Cosmostigma occurring in Thailand. Cosmostigma racemosum, Pentatropis capensis and Periploca cordata are typified.