Three hundred and four hypertensive patients with different degrees of left ventricular hypertrophy (LVH) were recruited and followed for 4 years. The patients were randomized into two groups: Group I (150 patients) was treated with a combination of hypotensive drugs including beta-blockers, and group II (154 patients) was treated with the same combination of drugs including diuretics instead of beta-blockers. By the end of the fourth year, 60 endpoints were recorded: 17 strokes, 13 myocardial infarctions, and 30 cases of chronic coronary insufficiency. Mortality was statistically higher in group II (7 of 154 or 5% v 1 of 150 or 1%) (P less than .035), but there was no difference between the groups in the incidence of nonfatal endpoints. These data confirm that beta-blockers can reduce mortality associated with the complications presented in hypertensive patients. Increased left ventricular myocardial mass (greater than 200 g, according to Teichholz' formula) was shown to have prognostic value for the development of complications. In patients with LVMM greater than 200 g, the probability of fatal complications was higher (P less than .007), as was the probability of nonfatal myocardial infarction (P less than .01), development of coronary artery disease (P less than .02), and all complications (P less than .0003). Regression of LVH to less than 200 g (according to Teichholz' formula) improved prognosis.