A cross-sectional study on the prevalence of atherosclerotic vascular disease (ASVD) and its risk factors in non-insulin-dependent diabetic and nondiabetic subjects was carried out from 1982 to 1984 in East Finland (Kuopio) and West Finland (Turku), two areas known to differ markedly in prevalence of ASVD in the nondiabetic population. A total of 510 diabetic and 649 nondiabetic subjects aged 45-64 yr were examined in East Finland and 549 diabetic and 724 nondiabetic subjects of the same age in West Finland. In both areas and in both sexes the prevalence of coronary heart disease (CHD), stroke, and intermittent claudication was higher in diabetic than in nondiabetic subjects. Both in diabetic and nondiabetic subjects the prevalence of ASVD was higher in East Finland than in West Finland. In men, the East-West difference in the prevalence of symptomatic CHD and claudication was greater in diabetic than in nondiabetic subjects. In both areas and in both sexes the serum lipid pattern was more atherogenic and hypertension was more frequent in diabetic than in nondiabetic subjects. In both diabetic and nondiabetic subjects, serum total-cholesterol level was somewhat higher and hypertension was more frequent in East Finland than in West Finland. The East-West difference in serum total-cholesterol was greater in diabetic than in nondiabetic subjects. In multiple logistic analyses including cardiovascular risk factors, diabetes status, and area of residence, residence in East Finland was found to be, in addition to diabetes, a strong independent factor associated with CHD, particularly in men.