Objectives: Leptin has a significant role in body weight regulation and energy balance. We examined the effect of tibolone on the body weight and serum leptin levels in postmenopausal women. Study design: Twenty women (aged 43-60 years) participated in this prospective study. All women in this study protocol received 2.5 mg/day of tibolone. Absolute and body mass index (BMI)-corrected serum leptin concentrations and BMI values were measured at baseline, after 3 months, and after 6 months of the tibolone therapy. Results: Tibolone did not affect absolute and BMI-corrected serum leptin levels, and BMI values during the treatment. A significant linear correlation between BMI values and serum leptin levels was observed (p<0.05, r=0.67). Conclusions: Tibolone seems not to affect serum leptin levels, body weight and BMI values of postmenopausal women. There is a significant correlation between serum leptin levels and BMI values. © Springer-Verlag 2004.