The present study aims to evaluate the effects of orlistat-assisted weight loss on endothelium-dependent vasodilation by ultrasonography in obese Chinese subjects with hypertension. Thirty obese hypertensive patients (mean age: 46.6 +/- 10.3 yr, male:12) were given 120 mg of orlistat 120 mg three times daily for 12 weeks, without a concomitant hypocaloric diet or anti-hypertensive drugs. Fifteen concurrent blood pressure, age, and gender-matched, nonobese hypertensive patients (mean age: 46.6 +/- 11.3 yr, male:6) served as the control. The height, body weight, waist circumference (WC), and blood pressure were measured and flow-mediated dilation (FMD) and the nitroglycerin-mediated dilation (NMD) of brachial artery was determined by high-resolution ultrasound before and after 12 weeks treatment with orlistat. The baseline parameters were comparable between the two groups, while body mass index (BMI) and WC were greater in the obese group (p < 0.01). Before treatment, the brachial artery diameter was increased by 9.6% following reactive hyperemia in the obese group, significantly lower than that in the control group (13.3%, P < 0.01). Nitroglycerin-mediated dilation was not difference between the two groups. After 12 weeks of orlistat treatment, the brachial artery diameter was increased by 14.2%, and the FMD was significantly improved (P < 0.01), associated with a significant reduction in weight, BMI, WC, and blood pressures. Nitroglycerin-mediated dilation was not significantly affected. On multiple regression analysis, improvement in FMD was determined by change of body weight (Beta = -0.555, P = 0.001), after adjustments for height, heart rate, systolic blood pressure (SBP), diastolic blood pressure (DBP), and WC. Orlistat can effectively reduce body weight and blood pressure and improve endothelium-dependent FMD in obese Chinese hypertensives.