Schistosoma japonicum from the People's Republic of China is considered to represent a single species comprising either
1 or 4 ‘strains’. We conducted an allozyme electrophoretic study to examine the extent of genetic variation in S. japonicum
from mainland China. The allelic profiles of S. japonicum from 7 provinces were established at 16 enzyme loci. S. japonicum
from Sichuan had 3–5 (19–31%) fixed differences compared with those from Zhejiang, Anhui, Jiangxi, Hunan, Hubei and
Yunnan, suggesting that S. japonicum in mainland China represents a species complex. In addition, genetic markers were
also established for different laboratory-maintained populations of S. japonicum which has significant implications for
studying the biology of these organisms in human and animal hosts, and for the control and surveillance of human
schistosomiasis in China.