The purpose of this study was to examine the effects of a short-term resistance training program on serum leptin concentrations in obese adolescents. Eighteen Chinese obese adolescents participated in the supervised weight management program. Resistance training was conducted three times a week on alternate days for 6 weeks. Body composition [body fat mass (FM) and body lean mass (LM)] determined by dual-energy X-ray absorptiometry, muscle strength and leptin, insulin and glucose were measured before and after training. Subjects demonstrated significantly improved strength of leg, chest and bicep under conditions of stability in weight, FM and LM. There were positive correlations between leptin and body mass index, FM, %FM, waist girth and hip girth, and negative correlations between leptin and %L M at the resting state before and after 6 weeks of resistance training. No significant relationship was found between leptin concentration and the parameters of muscular strength or concentrations of insulin and glucose. Compared to pre-training values, serum leptin levels were not significantly altered, while relative leptin (leptin/FM) decreased significantly after the short-term resistance training. These results indicate that short-term resistance training enhances muscle strength but does not alter leptin levels in obese adolescents with weight and FM stability. The results also suggest that 6 weeks of resistance training decreases the requirement of leptin per unit of FM and improves leptin sensitivity in obese adolescents.