The present investigation was planned on four endogamous groups of Haryana viz. Banjara, Jatav, Nai and Rajput, and the distribution of serological traits, ABO and Rh (D) blood groups was determined. In the ABO blood group system the frequency of A allele ranged from 0.102-0.285, that of B allele ranged from 0.201-0.348 and of O allele from 0.370-0.654. In Rh (D) blood group system the frequency of d allele ranged from 0.000-0.583 while the frequency of D allele varied from 0.417-1.000. The frequency range of ABO alleles conformed to the range of other populations of North West India studied earlier whereas that of d allele deviated from the upper maxima.

Keywords: ABO; Allele frequency; Endogamous groups; Rh (D) blood group.