Abstract: The partial NADH dehydrogenase subunit 4 （pnad4） fragment was amplified by polymerase chain reaction （PCR） from Schistosoma japonicum collected from 4 areas in Hunan province， and the amplicons were cloned and sequenced. A 480 bp sequence was obtained and the nucleotide difference between samples from the four locations were 0.4％-1.3％. Low level of sequence variability between and within different populations of S.japonicum was detected. The results are worthwhile for further study on the population genetic structures of S.japonicum.

Key words: Schistosoma japonicum, NADH dehydrogenase subunit 4, Sequence analysis