Genetic polymorphism of two plasma proteins prealbumin ( PA ) and transferrin ( Tf ) , and two plasma isozymes, malate dehydrogenase ( MDH) and alcohol dehydrogenase ( ADH ) from 118 laboratory-bred Rhesus monkeys ( M.mulatta ) was analysed by thin-layer polyacry lamide gel electrophoresis.The result suggested that ADH showed the monomorphism, the PA.Tf and MDH showed the polymorphism.The electrophoric pattern of PA can be divided into 7 phenotyp s, that is AA, AB, AC, AD and BB, CC. EE. The genes frequencies of A, B, C, D and E were 0.343, 0.072, 0.042, 0.009 and 0.081 respectively .The Tf can be divided into 17 phenotypes, that is CC, DD, EE, FF, GG, CD, CE, CG, CH, DE, DF, DG, EF, EG, EH, FG.The genes frequencies of C, D, E, F, G and H were 0.064, 0.38, 0.133, 0.111, 0.244, and 0.014 respectively. The MDH isozyme can be divided into MDH1-1 and MDH2-1 two phenotypes MDH1 and MDH2 frequencies were 0.953 and 0.042. The experimen tal results were compared to those of previously reported experiments.