Systematic, simultaneous surveillance of cardiovascular disease risk factors, morbidity, and mortality is ongoing in the Minnesota Heart Survey. Risk factors for cardiovascular disease were measured in population-based surveys of Twin Cities metropolitan area residents aged 25-74 years in 1980-1982 and 1985-1987. During this period, age-adjusted, average systolic blood pressure declined nonsignificantly in men and significantly in women, and average, age-adjusted diastolic blood pressure declined 1.1 mmHg in men and 0.9 mmHg in women. Between 1980-1982 and 1985-1987, serum total cholesterol declined significantly, 5.2 and 5.8 mg/dl in men and women, respectively. Serum high density lipoprotein cholesterol decreased 1.6 mg/dl in men and 0.9 mg/dl in women. The prevalence of cigarette smoking declined by 14% in men and 18% in women. In contrast, the average body mass index increased 0.6 kg/m2 in men and 1.2 kg/m2 in women. Systematic hospital and death certificate surveillance found that mortality rates for coronary heart disease in the Twin Cities metropolitan area declined 20.1% in men and 12.9% in women from 1981 to 1986. Despite difficulties in interpretation of ecologic studies, it appears likely that improvements in population risk factor levels played a role in the decline in disease rates and could influence future mortality trends in this population.