Abstract: The objective of the present study was to estimate the allele and genotype frequencies of the BLAD, DUMPS and κ-CSN genes in Holstein young bulls of the national AI station of Iran. It is shown that the genetic mutation responsible for BLAD in Holstein cattle was absent in all young bulls entering to the national dairy cattle progeny test. Of the 37 young bulls genotyped for CD18/HaeIII gene mutation, 36 were normal homozygote (AA), 1 was heterozygote for the disease (AB) and no affected homozygote genotype (BB) were found. The frequency of the normal and BLAD mutant allele were 0.99 and 0.01, respectively. The analyzed results showed that the BLAD carrier prevalence in Iranian Holstein young bulls was approximately 2.8%. The genotype frequencies in κ-CSN/HinfI locus were 0.70 for homozygote (AA) and 0.30 for heterozygote (AB) animals while the frequency of the A allele was 0.85. In the present study it is shown that the genetic mutation responsible for DUMPS was absent in all of the young bulls analyzed from national AI station. It can be concluded that due to negative economical impact of the DUMPS and BLAD mutation on dairy cattle industry and their recessive mode of inheritance, attention has to be paid to any case of a young bulls entering to the testing program having in his origin any known carriers. Such a bull should be tested and if positive eliminated from the active population. Young bulls (under progeny testing program) should also be screened for both mutated alleles if in their progeny a high incidence of mortality is observed. This strategy would prevent the introduction of these mutated alleles in the Iranian endogenous cattle breeds.