The Multiple Risk Factor Intervention Trial was a large collaborative primary prevention trial designed to test the effects of lowering cardiovascular risk factors (ie, diastolic blood presure [DBP], serum cholesterol, and cigarrete smoking) on mortality rate from coronary heart disease in 12,866 high-risk men aged 35 to 57 years. Men were randomly assigned to either special intervention (SI) or usual care (UC) groups. Usual care men were referred to their regular source of medical care. Special intervention men were seen frequently and underwent intensive intervention initially followed by maintenance intervention in 22 different clinical centers. Hypertension intervention in SI men primarily consisted of a stepped-care pharmacologic approach designed to lower blood pressure (BP). After six years, 58.2% of SI men and 47.0% of UC men were given antihypertensive medication. In both study groups, mean systolic and diastolic BPs decreased from baseline; after six years, overall DBP was 3.2 mm Hg lower in SI men compared with UC men. In hypertensive men (DBP≥90 mm Hg or those taking antihypertensive medication at baseline), after six years, DBP was 4.4 mm Hg lower in the SI group compared with the UC group. Use of specific antihypertensive agents differed substantially between the two groups. Self-reported complaints while taking antyhypertensive drugs were minimal in both groups. Weight loss was associated with BP lowering in both study groups, regardless of treatment status.