OBJECTIVE To compare weight loss efficacy, safety and tolerability of sibutramine and placebo in mildly to moderately obese hypertensive subjects; to assess the effect of weight loss on blood pressure. METHODS Randomized, double-blind, parallel-group; 3-week placebo run-in and 12-week treatment phase. METHODS Nine hospital outpatient clinics and general practices in the Netherlands. METHODS 127 men and women, 18-65 years old, with body mass indices (BMI) ranging from 27 to 40 kg/m(2) and stabilized hypertension - mean resting diastolic blood pressure of 90-120 mm Hg - with or without antihypertensive medication. METHODS Sibutramine 10 mg once daily; placebo. METHODS Body weight, blood pressure, routine laboratory and clinical safety monitoring. RESULTS Of 113 evaluable patients, 54 received sibutramine and 59 placebo. Weight reduction was significantly greater with sibutramine from week 2 onwards (last observation carried forward): mean, 4.4 kg with sibutramine and 2.2 kg with placebo (p = 0.002); mean percentage weight reduction, 4.7 and 2.3%, respectively (p < 0.001); mean BMI reduction, 1.6 and 0.8 kg/m(2), respectively (p < 0.01). Reduction in excessive body weight was associated with a reduction in blood pressure in both groups, although the mean reduction in supine diastolic blood pressure was numerically, but not statistically significantly, greater in the placebo group (5.7 mm Hg) compared with the sibutramine group (4.0 mm Hg; p = 0.21). Similar reductions were seen in supine systolic blood pressure. Both treatments were well tolerated. CONCLUSIONS Sibutramine 10 mg once daily is a useful, effective therapy for obesity in the presence of stable hypertension.