Abstract: Summary Genetic polymorphism of soluble Glutamic-Pyruvic Transaminase (GPT) was first described by Chen et al in 1971. Three common phenotypes were found. The three phenotypes are controlled by a pair of alleles Gpt~1and Gpt~2 at an autosomal locus. The polymorphism of GPT have been studied in different population groups and so far little information is available for China. This paper reported the polymorphism of GPT examined in 277 normal unrelated donors living in Guangzhou. Enzyme typing was carried out for starch-gel and polyacrlamide-gel electrophoresis and the specific enzyme staining. The gene frequencies of Gpt~1 and Gpt~2 were estimated at 0.525 and 0.475. The observed numbers of the phenotypes were in good agreement with the numbers expected under the Hardy-weinberg equilibrium (x~2=1.802,0.2>p>0.1). The paternity exclusion rate and DP (Discriminating Power) were estimated at 0.187 and 0.642. The activity of the three phenotypes were measured in the red cell lysates. The mean activity of GPT phenotypes were 4.433±0.643 EU/gHb for GPTl,2.900±0.835 EU/gHb for GPT2-1 and 2.433, ±0.870 EU/gHq for GPT2. The GPT phenotypes of bloob stains adhered to gauze, filter paper, white cotton cloth and glass plate can be detected at 4℃ for two weeks, 52?? for four days and 37℃ for one day. GPT1 has longer examinable time than GPT2-1 and G PT2. It may be seen that the examination of GPT phenotypes is one of the available technique for determination of paternity and identification.