Obesity and arterial hypertension are important public health problems. Both overweight and hypertension predispose to cardiovascular diseases, such as myocardial infarction, stroke and renal failure. Moreover, overweight clearly predisposes to hypertension, and thus to an increased prevalence of cardiovascular diseases. This in turn favors inactivity and further weight gain, leading to an exacerbation of cardiovascular disorders. Obesity, hypertension and cardiovascular diseases thus contribute to three corners of a vicious triangle. It is within this conceptual framework that this paper reviews the pathogenesis of obesity-related hypertension, which is highly complex. Many factors act together to promote vasoconstriction and sodium retention. Leptin, free fatty acids and insulin, whose levels are increased in obesity, may act synergistically to stimulate sympathetic activity and vasoconstriction. In addition, obesity-induced insulin resistance and endothelial dysfunction may operate as amplifiers of the vasoconstrictor response. Finally, increased renal tubular reabsorption of sodium may also occur, caused by an increased renal sympathetic nerve activity, the direct effect of insulin, hyperactivity of the renin–angiotensin system and possibly by an alteration of intrarenal physical forces. All together, these factors will lead to sustained hypertension. Because the prevalence of obesity was steadily increasing in the last decades, leading to an increased prevalence of hypertension and cardiovascular disorders, obesity and hypertension will most likely become the health challenges of the twenty-first century.