One hundred and seventy Sudanese patients suffering from vitiligo were investigated for the distribution of A1A2BO, MNSs, Rhesus (genotypes), Kell and Duffy blood groups. The same genetic markers were investigated in Sudanese controls, consisting of two series: a published population series and a random sample of healthy blood donors. The relative frequencies of these blood groups were examined between the vitiligo patients and either or both of the control series. There was no significant association of ABO, Ss, Rhesus, Kell and Duffy blood groups in vitiligo. However, a significant association was observed with the MN system with an excess of homozygotes and of the M gene in vitiligo.