The kidney plays a relevant role in the origin of essential hypertension in humans, and it suffers the consequences of sustained elevated blood pressure in the absence of therapy. Recently, a relevant prevalence of mild renal insufficiency both in general population than in hypertensive patients has been described. A direct relationship seems to exist between the level of cardiovascular risk and the prevalence of the renal disorder, whether this is detected as an elevation in serum creatinine or as a diminution of estimated creatinine clearance. This renal function impairment is a strong predictor of cardiovascular risk in patients with chronic heart failure and following myocardial infarction. Prevention of renal and cardiovascular damage in these patients will be one of the most relevant tasks in the future. The aim of this short review is to discuss the evidence in favor of a relevant prevalence of mild renal insufficiency in hypertensive patients, as well as the association of this disorder with a very significant increment in global cardiovascular risk.