Obesity is one of the most frequently encountered medical problems of our time. Among the complications of this pathologic entity, renal disease is an important issue and its pathophysiologic mechanisms are a challenge for the physician, since a variety of etiologic factors are implicated in its genesis. For example, hypertension, hyperlipidemia and insulin resistance affect renal function, each one in a different way. Obesity seems to be a state in which kidneys demonstrate morphological and functional alterations, while hormonal and growth factors play a significant role. Among them, leptin, a recently discovered cytokine, has undergone extended investigation and has proven to be a factor that contributes to renal disease, mainly through mechanisms that involve activation of the TGF-beta system resulting in glomerulopathy and related clinical symptoms. Experiments in animals have revealed interesting aspects as far as the role of leptin in kidney function. Understanding the underlying mechanisms of obesity-related glomerulopathy may become a valuable aid in handling an obese patient with renal disease and associated problems.