The association between renal dysfunction and cardiovascular risk in patients with hypertension and left ventricular hypertrophy (LVH) has not been specifically studied. The aim of this study was to analyze the association between renal function and the presence of cardiovascular disease in this group of patients. Hypertensive patients with electrocardiographic criteria for LVH were recruited in cardiology outpatient clinics from April 2003 until November 2004. Epidemiologic variables were determined, together with an estimation of the glomerular filtration rate by means of the Modification of Diet in Renal Disease (MDRD) and Crockoft-Gault equations. The population was classified according to the kidney disease stages of the National Kidney Foundation. A total of 3962 patients were included in the study, 47.6% of which were female, with a mean age of 67.2 years. The prevalence of established cardiovascular disease was higher in patients with a depressed glomerular filtration rate (68.3% vs 54.9%; P<.001). After adjusting for age, sex, body mass index, diabetes, smoking habits, and systolic and diastolic blood pressures, the stage of renal function was an independent predictor of the presence of cardiovascular disease (odds ratio, 1.5 [confidence interval, 1.19-2.02]; 2.1 [1.55-2.89]; and 2.6 [1.52-4.42], respectively, for stages 2, 3, 4-5, compared with stage 1). In hypertensive patients with electrocardiographic criteria for LVH, the determination of the glomerular filtration rate by the MDRD or Crockoft equations is easy and identifies a progressive and independent increase in cardiovascular risk.