Based on the examination of blood groups (ABO, Rh, MNSs, Duffy, Kell-Cellano, P, Kidd, Lewis, LW) the genetic polymorphism of the Gypsy population living in Hungary has been studied. Comparisons were made between Hungarian Gypsy and non-Gypsy populations, and significant differences were found in the incidence of most of the tested blood groups.