Abstract: Major Histocompatibility Complex (MHC) plays a pivotal role in antigen presentation for eliciting immune responses against invading pathogens. The best-characterized genetic control of disease resistance and immune response in animals are associated with MHC. Therefore in this study polymorphism of ovar-DRB1 in DNA samples of 111 heads Arabi sheep using Polymerase Chain Reaction (PCR) and Restriction Fragment Length Polymorphism (RFLP) method was examined. Identities of 18 different patterns and 8 distinct DRB1 alleles among Arabi sheep have been determined. There is not deviation in Ovar-DRB1 gene from Hardy-Weinberg equilibrium in this population results showed. Obtained results have revealed that the exon 2 region of ovar-DRB1 was highly polymorphic on Arabi sheep.