Starch gel electrophoresis was used to estimate the degree of genic variation and genetic relatedness among twelve populations of the Cat-Sanke(Elaphe diene) in Korea. Out of the 17 loci examined 9 loci (Mdh-2, Ldh-1, Ldh-2, Idh-1, Idh-2, Adh, Aco-3, ep, Got-1) were monomorphic with identical mobility in all populations, 4 loci (Pgm, Mpi, Pept-1, Got-2) were nearly identical with minor allele frequency differences, and 4 loci (Mdh-1, Fgi, Est-2, 6psd) showed moderate variation. Levels of genic variation were similar to those found for other reptilian species. The mean genetic similarity value(S) among twelve populations is 0.966. Chechu population was slightly remote genetically from the mainland populations.