The discovery of the obese gene in the mouse and its conserved homologue in humans has led to important discoveries in energy metabolism. One of the chief findings was the fact that the expression of the leptin gene was regulated and that it, in turn, could regulate metabolism and behavior. Much of the literature has focused on the physiological role of leptin in driving processes as diverse as reproduction, starvation defence, feeding behavior or body weight, all dependent on expression levels of the ob gene. Here, we will describe our work, in which we have begun to elucidate the regulatory processes controlling obese gene expression.