The genetic polymorphism of red blood cells soluble glutamic-pyruvic trans aminase (GPT) has been investigated in 5 popu lation groups in Israel: Ashkenazi Jews, non Ashkenazi Jews from Iraq, Yemen, North Africa, as well as some Arabs. The distribution of Gpt1 and Gpt2 genes among the five communities was not homogenous (χ2 = 4, d.f. = 25.67, p < 0.0005). The Yemenite and North African Jews had significantly lower frequencies of Gpt2 (0.2737 and 0.3290, respectively) than did the Ashkenazi and Iraqui Jews or Arabs (0.4005–0.4135).