Objectives To assess weight loss efficacy ,safety and tolerability of sibutramine in simple obese subjects.Methods Randomized, double-blind, placebo-controlled clinical trial. Four hospital outpatient clinics in Shanghai, Chongqing, Shandong and Tianjin, respectively. Participants: 233 men and women, 18-65 years old, with body mass index (BMI) ranging from 27 to 40*!kg/m2 were randomly divided into an intervened group and a placebo control group. Sibutramine 10 mg or placebo once a day. Main outcome measures: Body weight, routine laboratory and clinical safety monitoring.Results Of 233 eligible patients, 120 received sibutramine and 113 received placebo. Weight reduction was significantly greater in the intervened group (6.8±3.1) kg than the placebo control group (0.48±2.6) kg from week 4 onwards to week 24 (P<0.001). Some minor side effects were noticed in the subjects who took sibutramine. But the symptoms were light and short term. Sibutramine was will tolerated.Conclusions Sibutramine 10*!mg once a day is an effective an safe therapy for weight reduction in simple over-weighted and obese subjects.