Genetic variants of the two milk proteins, β-casein (β-Cn) and β-lactoglobulin(β-Lg), from 138 individual Holstein cattle reared in Korea were investigated by means of starch-gel-urea electrophoresis and their phenotypes, genotypes, gene frequencies, linkage of gene and genetic similarities were compared with those of foreign Holstein and other breeds. The results are summarized as follows: 1. The milk proteins were genetically polymorphic in cattle and were controlled by codominant autosomal allelic genes of βCn A1, βCn A2, β-Cn A3, and βCn B(4 types), and (β-Lg A and β-Lg B(2 types). 2. The phenotypes showed the following distribution of the two milk protein loci: β-Cn A1 A1 34, A1A2 55, A2A2 30, A1A3 4, A2A3 7, A1B 3, A2B 5; βLg AA 25, AB 73, BB 40. The numberofphenotypescorresponded closely to expectations of Hardy-Weinberg equilibrium (β-Cn: 0.9 $gt;P $gt; 0.8, β-Lg: 0.7 $gt; p$gt;0.5). 3. Gene frequencies for genetic variants of the milk protein loci were determined by counting identified alleles. In the β-Cn loci, the β-Cn A1 and A2 variants were predominant with a frequency of 0.471, 0.460, respectively. However, the β-Cn A3 and β-Cn B genes were rare (0.040 and 0.029, respectively). Gene frequencies of β-Lg were 0.446 and 0.554 for alleles A and B, so frequency of the β-Lg^B variant was slightly higher than that of β-Lg A variant. 4. Genetic linkage of the casein loci was αs₁-Cn^B/β-Cn^A 116, αs₁-Cn^(BC)/β-Cn^A 14, and αs₁-Cn^(BC)/β-Cn^(AB) 8. The most close linkage of gene between the αs₁-Cn^B and β-Cn^A has been observed. 5. These results indicate that gene frequencies of the milk protein loci of Holstein cattle in Korea are fairly similar to those of foreign Holstein, but are markedly different from those of other European dairy breeds and Korean native cattle, especially Hariana breeds of Zebu.