Weight reduction was compared with metoprolol (200 mg daily) in a randomized placebo-controlled trial of first-line treatment of mild hypertension (diastolic blood pressure 90–109 mm Hg) in 56 overweight patients aged under 55 years. After 21 weeks of follow-up the weight-reduction group had lost an average of 7.4 kg. The fall in their systolic pressure of 13 mm Hg was significantly greater than that in the placebo group (7 mm Hg) but not different from that in the metoprolol group (10 mm Hg). Their fall in diastolic pressure (10 mm Hg) was greater than that in both the metoprolol (6 mm Hg) and placebo (3 mm Hg) groups. At the end of the follow-up period, 50% of patients in the weight-reduction group had a diastolic pressure of less than 90 mm Hg. In the weight-reduction group, left ventricular mass decreased by 18% in comparison with placebo; in the metoprolol group left ventricular mass was unchanged. In the weight-reduction group there was a decrease both in total cholesterol and in the ratio of total to HDL-cholesterol; in the metoprolol group there was a decrease in high density lipoprotein(HDL)-cholesterol and an increase in the ratio of total to HDL-cholesterol. In this study, weight reduction produced significant falls in both blood pressure and left ventricular mass but not the adverse effects on plasma lipids commonly associated with antihypertensive drug therapy.