This field study investigated the distribution of the freshwater snails of the family Ampullariidae in 18 provinces of Thailand. The introduced Pomacea canaliculata has wide distribution in the studied provinces. Pila angelica, P. ampullacea and P. pesmei still have limited distribution. Pila polita, which is absent in the south, now can be found in Phangnga, a southern province of Thailand. Moreover, P. polita is currently used as a traditional medicine of the local people for the treatment of a skin disease.