Serum samples from Armenians, and from Libyan and Ashkenazi Jews living in Israel were tested for Gm (1, 2, 3, 5, 6, 10, 11, 13, 14, 17, 21, 24, 26) and for Inv(1) [Km(1)]. The Gm data indicate that all three populations have Negroid and Mongoloid admixture. The minimum amount of admixture varies from 3.1% (Armenians) to 5.5% (Libyan Jews). This admixture had not been detected by the study of other polymorphisms, thus once again underlining the sensitivity of the Gm system. The haplotype frequencies among the Libyan Jews are markedly different from those among the Ashkenazi Jews. Surprisingly (coincidentally?) the haplotype frequencies among the Ashkenazi Jews and the Armenians are similar. The Libyan Jews have a significantly higher frequency of Inv1 than do the Ashkenazi Jews and among the latter, Inv1 is at least twice as frequent among Polish Jews as it is among Russian Jews.