OBJECTIVE This work was done to determine the role of hypertension treatment in the prevention of disease progression, left ventricular hypertrophy and congestive heart failure. BACKGROUND Lowering of blood pressure in hypertensive patients has been reported to reduce morbidity and mortality from strokes and myocardial infarction. Data on primary prevention of disease progression, left ventricular hypertrophy and congestive heart failure have not previously been carefully quantified. METHODS All the major long-term hypertension treatment trials over the past 20 years were reviewed. RESULTS One thousand four hundred ninety-three of 13,342 subjects in the control groups compared with only 95 of 13,389 in the treated groups progressed from less severe to severe hypertension. The incidence of left ventricular hypertrophy in treated compared with control or placebo subjects was 140 of 6,150 and 216 of 6,098 subjects, respectively; congestive heart failure occurred in 240 of 6,923 subjects in the control group compared with only 112 of 6,914 treated subjects. CONCLUSIONS The lowering of blood pressure over a 3- to 5-year period of time is effective in preventing severe disease, left ventricular hypertrophy and congestive heart failure in addition to strokes and myocardial infarction. In an era when expensive and often complicated methods are being used to prevent recurrence of congestive heart failure or myocardial infarction, it is important to highlight the role of antihypertensive therapy in primary prevention.