ATP-binding cassette superfamily G member 2 transporter (ABCG2) is located in membrane of mammary glands alveolar epithelial cells in cows that actively extrudes xenotoxins and drugs into milk from blood. Polymorphism of the ABCG2 gene have been found to be associated with milk yield and composition in cattle. In the present investigation, Sahiwal and Hariana cattle were studied for polymorphism of ABCG2 gene by PstI/PCR-RFLP assay. The RE digestion of the 292 bp PCR product showed the presence of AA genotype with a genotypic frequency of 1.0. AC and CC genotype were not observed in screened

samples. The allelic frequency of ABCG2-A allele was calculated as 1.0 and that of ABCG2–C allele was zero. The present study revealed monomorphic nature of ABCG2 gene in the screened samples of Sahiwal and Hariana cattle breed.