Twenty nine species in 14 genera of plant-parasitic nematodes were collected and identified from mainly upland fields and orchards in Thailand from 1987 to 1990. Pratylenchus sp. was detected in this study and described as a new species, P.subranjani in 1990 and following six species were recorded for the first time in this country : Echphyadophora quadralata, Helicotylenchus certus, Pratylenchus pratensiobrinus, Tylenchorhynchus maqbooli, T.leviterminalis and T. obregonus. For the identification of Meloidogyne spp. in Thailand, measurements of the second-stage juveniles of four species were performed.