The aim of the present study was to examine the effect of aerobic training and green tea supplementation on serum leptin and insulin resistance in overweight and obese men. For this purpose, 43 overweight and obese men were selected voluntarily and were included in four groups: control (body mass index 31.4+3.7, VO2max 39.3+3.8 ml/kg.min), green tea supplement (body mass index, 30.3±2.8 k/m2, VO2max, 40.6±4.1 ml/kg.min), exercise (body mass index, 30.6±4.2 k/m2; VO2max, 38.7±5.6 m/kg.min), combined exercise and green tea supplement (body mass index, 30.9±2.6 k/m2; VO2max, 40.3±3.1ml/kg.min). The exercise group performed the aerobic program for 10 weeks, three sessions per weeks with an intensity of 65 to 75% of maximal heart rate. Green tea supplement group consumed daily three green tea bags (2 gr. each bag). The combined exercise and green tea supplement group had the two interventions. Before and after the investigation, fasting blood samples of all subjects were collected. The data were analyzed by one-way ANOVA and ANCOVA tests. Results showed that aerobic training, green tea supplement and combination of aerobic training and green tea supplement did not significantly change serum leptin levels and insulin resistance index. Green tea supplement significantly decreased weight and body mass index. Aerobic training significantly decreased weight, body mass index and body fat percentage. Combination of aerobic training and green tea supplement significantly increased maximal oxygen consumption and significantly decreased weight, body mass index and body fat percentage. It can be concluded that aerobic training and green tea supplement did not have a significant effect on serum leptin levels and insulin resistance index. However, to achieve more conclusive results, further investigation is warranted.