Abstract: 　Objective To study the variation of Schistosoma japonicum through two mitochondrial DNA molecules. Methods Genomic DNA was isolated with kit, and the mitochondrial NADH dehydrogenase 1(ND1) and cytochrome c oxidase I(COI) gene fragments were amplified by polymerase chain reaction(PCR) and sequenced. The gene trees were constructed and the acquired data were analyzed with the help of bioinfotmatics. Results The gene trees showed that the Taiwan isolate and the mainland isolates can be divided in two groups: a group from the hilly region (Yunnan and Sichuan), another group from the lake region (Hunan, Jiangxi and Anhui); isolates from Hubei are at a different position on the gene trees. Conclusion There are variations among the geographic isolates of Schistosoma japonicum in China, nevertheless, they have close kinship.

Key words: Schistosoma japonicum, Geographic isolate, Mitochondrial NADH dehydrogenase 1, Cytochrome c oxidase I, Genetic variation, Gene trees