The polymorphism of kappa-casein (alleles A, B and E) and growth hormone (alleles L and V) genes was studied using PCR/RFLP method with the aim to evaluate the degree of genetic diversity of Polish Red and German Red cattle, which are endangered with extinction. At the kappa-casein locus, a very low frequency of allele B in German Red cattle was found. In both the breeds, allele E was absent. There was a relatively high frequency of allele L in the growth hormone locus, especially for German Red cattle. The results were compared with frequencies and diversities of other red cattle breeds.