As a result of extensive surveys of sand flies carried out during 1987-90 in Thailand, species including a man-biter, Phlebotomus hoepplii, and cattle-biters, P. argentipes and P. major major, were discovered in Kanchanaburi Province. The human-baited catches revealed a low density of P. hoepplii and the biting occurred during 2100-2300 hours. Phlebotomus hoepplii was also found feeding on buffalo and inhabiting Pha-Thai Cave, Lampang Province. Phlebotomus argentipes was also a common cave-dweller and therefore had a wider distribution than P. major major, which was only collected in Sara Buri and Kanchanaburi provinces. The 3 species inhabited forest environments close to foothills and on stream banks. Although there is yet no evidence that they are involved in leishmaniasis transmission, the bionomics of the species are of importance and should be studied further.