The nomenclature of genetic variants of casein which is major protein in milk have had a lot of confusion, but now have established. Genetic variants of ${alpha}_{s1}-CN,;{alpha}_{s2}-CN,;{eta}-CN,;{kappa}-CN$ have reported 8 variants(A, B, C, D, E, F, G, H), 4 variants(A, B, C, D), 13 variants ($A_1,;A_2,;A_3,;A_4$, B, C, D, E, F, G, $H_1,;H_2$, I), 11 variants(A, B, C, E, $F_1,;F_2,;G_1,;G_2$, H, I, J), respectively. Their data detailed have introduced in several web sites including www.uniprot.org. The studies on genetic variants of casein from Korean native cattle have been reported only ${eta}-casein;A_4$ but still not established the protein sequence. The classification and distinct nomenclature of genetic variants of bovine casein were required because the development of milk science and technology have been focused in the region that have to studied biochemically such as functional foods, EMC and GMO et al.