The adipose tissue is regarded as an endocrine organ secreting a number of peptide hormones, collectively called adipokines and involved in the regulation of several physiological functions, including energy metabolism and reproduction. Leptin is the most studied adipokine. Its circulating levels mostly reflect the adipose mass and are modulated by male and female gonadal steroids in opposite ways. Leptin displays a relevant role in the control of food intake and energy expenditure, representing a signal of satiety to the hypothalamus and a stimulus to increase energy expenditure. Moreover, its rise at puberty is believed to contribute to the hypothalamic activation that leads to the development and maintenance of a mature reproductive function. Several effects of leptin on reproduction are mediated by direct and indirect effects on gonadotropin-releasing hormone (GnRH)-secreting neurons in the hypothalamus. Interestingly, cytokines structurally related to leptin and interleukin-6, like ciliary neurotrophic factor and leukaemia inhibitory factor (LIF) are also functionally correlated with leptin in these actions. The other adipose product adiponectin increases the sensitivity of peripheral tissues to insulin and induces fat oxidation. Conditions of insulin-resistance, like diabetes and obesity, are characterized by reduced adiponectin levels. Another adipokine, resistin, is associated with the induction of insulin resistance. It is also expressed in the rat testis and it appears to be a mediator of energy homeostatasis and reproduction. Thus, recent evidence suggests that the physiology of the adipose tissue appears to be an important component in the regulation of reproduction and metabolism, with potential roles in human disease.