Investigation was undertaken to characterize different allelic variants of the MHC (Major Histocompatibility Complex) gene in mastitis and mastitis free cattle. Blood samples of mastitis resistant (25) and mastitis susceptible (35) animals of Maharashtra State (based on the history of absence or occurrence of mastitis for first three lactations) were used for DBA isolation. A 284bp fragment of MHC class-II gene of DRB3.2 locus having relation with occurrence of mastitis, was successfully amplified and digested with Rsa-I restriction enzyme. Nine genotypes, viz., d/d, n/n, j/l, k/k, o/o, l/l, l/n, l/o, x/x with frequency ranging from 0.033 to 0.38 and seven alleles viz., d, n, j, l, k, o, x with frequency ranging from 0.033 to 0.43 were observed. The result revealed that genotype l/l was observed only in healthy animals where as genotype n/n only in the mastitis affected animals. Rest of the genotypes were present in both mastitis free and mastitis affected cattle. This study will be helpful in the marker assisted selection of animals on the basis of mastitis susceptible and resistant genotypes.

Keyword: BoLA-DRB3.2 gene; PCR-RFLP;