Published data from the Veterans Administration Cooperative Study of Hypertension demonstrated that reduction in morbidity and mortality could be attained by treating men with fixed diastolic blood pressure over 105 mm Hg. Similar trends occurred for those with fixed diastolic blood pressure between 90 and 104 mm Hg. Results and current trends from other studies supported these findings. However, prior to inception of the Hypertension Detection and Follow-up Program (HDFP), it was not known whether benefits from antihypertensive therapy applied to all hypertensives in the general population and whether making use of existing medical knowledge could significantly reduce morbidity and mortality from hypertension in communities.