The purpose of this pilot study was to compare the ability of sustained-release verapamil (verapamil SR) and trandolapril, both alone and combined in half doses, to reduce blood pressure in obese patients with mild-to-moderate essential hypertension. Twenty patients (13 men and 7 women) took part in the study. Ten (group A) received verapamil SR 240 mg/d, and 10 (group B) received trandolapril 2 mg/d for 6 weeks. All patients were then given both drugs in half-doses for 6 weeks. After combination therapy, group B received verapamil SR 240 mg/d, and group A received trandolapril 2 mg/d for 6 weeks. When verapamil and trandolapril were used alone, systolic and diastolic blood pressures decreased significantly in each group. However, systolic and diastolic blood pressures fell further when combination therapy was used and rose slightly when the treatment was changed again to single-drug therapy. Side effects were fewer during the combination therapy. Thus the combination of half doses of verapamil SR and trandolapril was more effective in reducing blood pressure in obese patients with mild-to-moderate essential hypertension than a full dose of either drug given alone.