In this study, 953 patients (48 percent men) more than 60 years old with mild to moderate hypertension (class I or II) were included. After a two-week wash-out period, a starting dosage of captopril--12.5 mg twice a day--was given. Patients were examined after one and three weeks and, subsequently, at monthly intervals for a total period of four months. The dosage was adjusted to a maximum of 50 mg twice a day plus, when needed, 25 mg of hydrochlorothiazide per day. Thirty-two patients were lost to follow-up, 10 withdrew because of inadequate control of blood pressure, and only 21 (2 percent) dropped out because of side effects. Mean blood pressure decreased from 184/104 to 152/87 mm Hg. The lowest dosage (25 mg a day) was sufficient to control blood pressure in 15 percent of patients, 31 percent needed 50 mg a day, and 24 percent required 100 mg a day. Hydrochlorothiazide was added to the captopril regimen in 30 percent. No substantial changes in biochemical variables or electrocardiographic results were observed. "Quality of life" (judged as physical fitness, positive well being, mood, and sexual desire) remarkably improved.