Blood samples from the Waskia and Takia populations of Karkar Island, Papua New Guinea, and other nearby mainland populations, were tested for genetic variation in blood group, serum protein and red cell enzyme systems. Polymorphic variation was present in the ABO, P, MNS, Rh, Lewis, Duffy, Kidd and Gerbich blood group systems, in the Hp and Tf serum protein systems, and in the acid phosphatase, 6-PGD, ADA, PGM, MDH, and G-6-PD enzyme systems. A small number of variants was found in other systems: there were 4 Lu(a+), 1 Kp(a+), 2 C variants in the acid phosphatase system, 6 LDH variants, 1 ADA3–1 and 1 AK2–1 sample. All samples were negative for the red cell antigens Cw, Vw, He, K, Jsa, Dia, Wra, Rd and Marriott, and no variation was observed in the PHI enzyme system. The results are discussed in relation to those obtained on other Papua New Guinea populations.