Obesity has a protective effect against osteoporosis and this effect has been attributed to a high body fat content. It has been shown that the leptin concentration is higher in obese patients. Leptin, the protein product of obesity gene, is a hormone produced in adipose tissue. Some studies suggest that endogenous leptin might influence bone metabolism in postmenopausal women. In this study, we investigated plasma leptin concentrations in postmenopausal women with osteoporosis and also analyzed the relationship between plasma leptin levels and bone mineral density (BMD) in order to understand the potential role of leptin in maintaining bone mass. Forty-two postmenopausal women with osteoporosis and thirty seven age and BMI-matched healthy postmenopausal women were included in the study. The mean femoral neck BMD value in the patient group was significantly lower than that in the control group (0.691±0.1 g/cm 1 and 0.863±0.1 g/cm 2, respectively; p< 0.001). The mean plasma leptin concentration in the patient group was not significantly different from that in the control group (p> 0.05). Plasma leptin levels were correlated with BMI in both groups (p< 0.001 in the patient group and p= 0.001 in controls). There was also a strong positive correlation between plasma leptin levels and% fat in both groups (p< 0.001 in the patient group and p< 0.001 in controls). But there was no correlation between plasma leptin levels and femoral neck BMD values in both groups. Our results do not support the hypothesis that leptin itself plays an important role in maintaining bone mass in postmenopausal women.