RESUMEN
A total of 13 allozymes of 7 populations of Oncomelania snails trom 7 provinces in the mainland China were examined by horizontal starch gel electrophoresis. Results demonstrated that out of 17 loci examined, 10 were monomorphic loci: Aldh,Ao,G6pd ,Gpdh,Hbdh,Ldh, Sdh,Est-2,Est-3,and Est-6,and 7 were polymorphic loci:Est-4,Est-5,Xdh,Mdh,Idh,Got and Ap. Banding pattern showed that six enzymes were polymorphic accounting for 46.15 % (6/13) of total enzyme systems examined. Results indicated that a certain of relative relation-ship was existed along with the significant variation presented based on their environment and location among the 7 populations of snails from the mainland of China. It was revealed that the 7 polymorphic loci were the important loci affecting the gentic variation in the differ-ent populations of Oncomelania spp.