Abstract: This paper reports the results of preliminary study on the specificity of red blood cell antigens from varieties (or strains) of carp (Cyprinus carpio L.). By means of hemagglutination and serological absorption tests, cross reactions between special antiserum and RBC of gynogenetic red carp F2 and gynogenetic red mirror carp F1 (RMGF1) were investigated. It was found that the reaction values are different between these strains, but the values of random samples in a strain are of the same level. These results show that the genes controlling the red blood cell allotypic antigens of carp are homogenous to a great degree in the same strain. Among these tested strains, R8305 and R8413 have the most close reaction values and their absorptions are also identical. It implies that R8305 and R8413 are very similar in their genotypes. The differences among three gynogenetic strains (R8305, R8413 and RMGF1) and normal red carp2 mirror carp and silver carp (Hypophthalmichthys molitrix) are quite obvious. It appears that the allotypic antigens of RBC are peculiar to given carp strain or variety, and it can be considered as one of the markers for fish strain identification.