During 2008-2009 2,401 Phlebotomine sand flies were collected in 14 limestone caves in Kanchanaburi Province, Thailand to determine the prevalence and type of cavernicolous species that have the potential to be leishmaniasis vectors. Twenty species belonging to the genera Chinius, Nemopalpus, Phlebotomus and Sergentomyia were identified. An additional man-biting species, P. major major was recorded for the first time in Thailand. Ecological observations of the habitats were made. It is expected the diversity of cavernicolous sand flies is more than currently known. An updated list of 26 phlebotomine species for Thailand is provided.