Quantitative traits locus for milk production traits has been described on centromeric end of bovine chro-mosome 14. Reports name the acyl coA: diacylglycerol acyltransferase (DGAT1) GENE as a potential candi-date GENE with dinucleotide substitution (AA to GC) in exon VIII which causes the change of lysine to alanine in amino acid (K232A).The aim of the present study was to estimate the frequency of DGAT1 K232A polymorphism in Iranian Holstein bulls as a potential quantitative trait locus (QTL) for marker as-sisted selection. Sample of 103 Holstein bulls from the Animal Breeding Center of Iran were genotyped for DGAT1 polymorphism (A and K allele). The PCR-RFLP technique was used to study the DGAT1 GENE polymorphism. Frequency of KK, KA and AA genotypes were 0.59, 0.41 and zero respectively. The allele frequencies of the DGAT1 GENE were 0.7961 and 0.2039 for K and A allele, respectively. The K allele was sequenced and registered in NCBI GENE bank with EU075528 accession number.