Polyacrylamide gel electrophoresis was used to reveal the esterase isozyme patterns of a freshwater snail, Semisulcospira gottschei, in the lake Uiam. From the result with inhibitors, it is tentatively concluded that four types (arylesterase, carboxylesterase, acethylesterase, acethylcholinesterase)of the adult(means of allele per locus=1.16, %polymorphism=16.7, heterozygosity=0.082)was lower than the juveniles(A=1.7, %P=16.7, H$sub$D/=0.2215).