Secular trends in skinfold thicknesses and body fat distribution were examined in the adult Inuit of Igloolik, N.W.T. through surveys conducted in 1969/70, 1979/80 and 1989/93. Findings were compared with the nGanasan population of Volochanka (Taimir peninsula, Siberia), who were examined in 1992/3. The skinfold readings of the Inuit have increased over the two decades of observation. Currently, the young male Inuit and nGanasan remain relatively thin, but older Inuit men and the women of both populations are now quite obese relative to subjects from Southern Canada. The male Inuit have also developed a centripetal, coronary-prone pattern of fat distribution, with subscapular/triceps skinfold ratios that now exceed averages for southern Canada. The majority of both Inuit and nGanasan are current smokers and many fail to meet minimal standards of aerobic performance. Plasma cholesterol levels are still not very high, but a substantial proportion of the nGanasan are affected by hypertension; their source of animal protein is reindeer meat rather than the marine mammals eaten in Igloolik. Alcohol consumption is also higher in Volochanka than in Igloolik. Action is needed to control smoking, reduce body fat content and increase physical activity if circumpolar populations are not to experience an epidemic of cardiovascular disease.