One of the main advances in the field of metabolic control of body weight and obesity treatment was the identification of the OB protein or leptin, that plays an important role in controlling body weight, signalling to the CNS the amount of body fat. Indeed, leptin levels are positively correlated to indices of body fat, namely total fat mass, percent body fat and body mass index (BMI). This protein may be also the signal that indicates the nutritional status to the reproductive axis. Whether this signal is exerted directly on the gonads or through the neuroendocrine axis is still to be determined. A sexual dimorphism between male and female in serum leptin levels has been observed, with the latter showing higher serum leptin levels. This evidence has led to the hypothesis that estrogens might have a stimulatory role in leptin secretion. To evaluate this hypothesis, several authors have determined serum leptin levels in postmenopausal women that have estrogen levels comparable to those present in men. The results of these studies are contradictory and the aim of this article has been the revision of data present in the literature regarding serum leptin levels in menopause and to correlate them to body composition changes taking place during menopause.