Chinese and Japanese population of Chlamysfarreri and their reciprocal hybrids were surveyed in isozyme variability at 13 loci by polyacrytamide gel electrophoresis (PAGE). Isozyme banding patterns indicated these hybrids were diploid.Loci that were observed as being monomorphic in inbred populations of C. farreri were also found to be monomorphic in filial progeny;loci that observed to be polymorphic in parental type generations were also polymorphic in hybrid generations.Differences existed among allelic frequency of the four types of cross.Within the reciprocal hybrids the expression of malic enzyme (ME) isozyme was sufficient to distinguishing individual hybrids because of the band, Rf=0.38. However, there were no noticeable variations among all the samples to differentiate one from another. Inbreeding was likely to be the main problem in aquaculture. The introduction of new broodstock can improve the genetic diversity. Hybrid vigor has manifested to a certain extent in the present study.