Frequencies of 10 polymorphic systems were investigated in two ethnic groups (Turkoman and Bandari) living near the northern and southern borders of Iran, respectively. A further 6 blood group and enzyme systems were also investigated in Bandari alone and 4 in Turkoman alone. 4 out of 10 commonly studied systems (ABO, Rh, AP and Tf) showed significant frequency differences between these populations. Wright’s FIS indicates moderate isolation of these groups, and the gene frequency differences are therefore interpreted as indicating the differing origins of these populations.