A taxonomic revision of Micronychia Oliv. (Anacardiaceae: Rhoideae) is presented, a genus of trees and shrubs endemic to Madagascar. A key and descriptions are provided, and distribution, habitat and phenology of each species are also discussed. Five species and one variety are recognized, one of which is described as new, M. acuminata Randrianasolo, which is easily distinguished from the other members of the genus by its small and long acuminate leaves.