A polymerase chain reaction-restriction fragment length polymorphism test was performed on DNA samples extracted from blood samples of 256 Holstein Friesian crossbred and 112 from Jersey crossbred bulls/bull calves to detect allelic frequency of the bovine kappa-casein and beta-lactoglobulin gene responsible for milk production traits. A 350 bp fragment of kappa-casein and a 247 bp fragment of beta-lactoglobulin were amplified and digested with Hinf I and Hae III restriction enzymes, respectively. In the study, 2 types of alleles A and B and 3 types of genotypes AA, BB, and AB for kappa-casein and beta-lactoglobulin were observed. The results indicated that allelic frequency of kappa-casein for A-allele (0.66) was higher compared to B-allele (0.34). Similarly, B-allele frequency (0.72) of beta-lactoglobulin was much higher compared to A-allele (0.27) in crossbred dairy bulls. Kappa-casein and beta-lactoglobulin are useful markers for milk production traits on which bulls can be evaluated and selected for future breeding programmes.