Blood pressures from a 1980-1981 survey of 1,656 adults in Minneapolis-St Paul were compared with BPs from a similar community survey of 3,475 adults conducted in 1973-1974. Mean age-adjusted BPs in 1980-1981 were 3 mm Hg lower for mean and 2 mm Hg lower for women than in 1973-1974. Hypertension prevalence, defined as diastolic BP of 95 mm Hg or greater and/or use of antihypertensive medication, was essentially unchanged. In 1973-1974, however, only 40.4% of hypertensive persons had adequately controlled BPs, 13.7% were treated but had conditions that were uncontrolled, 20.4% had known hypertension but were untreated, and 25.5% had previously undetected hypertension. In 1980-1981, the respective percentages were 76.1%, 8.5%, 8.8% and 6.6%. These impressive changes in hypertension detection and control may have contributed to the recent decline in cardiovascular disease mortality in this community.