ABSTRACT A taxonomic revision of the Violaceae for the Flora of Thailand has been conducted based on field observations and by examination of herbarium specimens at BK, BKF, CMU, E, K, L, P and QBG. Three genera and 22 species are enumerated, viz.Hybanthus enneaspermus (L.) F. Muell., a widespread species in tropical Africa, tropical Asia and Australia which only found restricted to the north-eastern region, 11 species in Rinorea Aubl. and 10 species in Viola L. including 2 introduce species. Viola angkae Craib is endemic to northern Thailand. One species in Rinorea might be new to science. An account of species and their distribution are provided.