Leptin is the protein product of the obese (OB) gene in human. The known association between leptin and adiposity, and the suggested role of leptin in the control of body weight, led to the present study which was planned to examine the efficacy of conservative treatment (including low caloric diet, aerobic exercise and acupuncture) on serum leptin levels in obese subjects. Samples from 85 subjects were collected and classified according to BMI into controls and obese and the obese group was subclassified according to the type of intervention into subgroups low caloric diet, aerobic exercise, acupuncture. Leptin levels were higher in obese than in controls. Serum leptin levels were positively correlated with body weight, BMI, systolic and diastolic blood pressure in all groups and positively correlated also with serum ALT, and AST activities in obese subjects. This work confirms the other studies which suggested that human obesity is probably due to insulin resistance and that aerobic exercise best affecting serum leptin, lipid profile and blood pressure while low caloric diet best affecting body weight.