This study was performed to find genetic polymorphisms of κ-casein and β-lactoglobulin loci in Hanwoo using the PCR-RFLP. Genomic DNA was prepared from the blood of 327 Hanwoo. Amplified products of 530bp and 262bp fragments were obtained from the amplification of K-casein and β-lactoglobulin loci by PCR. The K -casein AA genotype showed a 530bp fragment in amplified products of K -casein loci with the restricted enzyme digestion of Taq I. The κ-casein AB genotype showed 530bp, 3446p and 186bp fragments and BB genotype showed 3446p and 186bp fragments. The β-lactoglobulin AA genotype showed 153bp and 109bp fragments in amplified products of β-lactoglobulin loci with the restricted enzyme digestion of Hae III. The β-lactoglobulin AB genotype showed 153bp, 109bp, 79bp and 74bp fragments and BB genotype showed 109bp, 79bp and 74bp fragments. The κ-casein genotype of Hanwoo gave frequencies of 45.9%, 37.7% and 16.4% for AA, AB and BB types. The rc-casein A and B alleles were 0.647 and 0.353, respectively. The β-lactoglobulin genotype of Hanwoo gave frequencies of 6.4%, 28.8% and 64.8% for AA, AB and BB types. The β-lactoglobulin A and B alleles were 0.208 and 0.792, respectively.