Background: Several studies have shown that albuminuria is associated with increased risk for fatal and nonfatal cardiovascular events, independent of conventional risk factors. The partition values for urine albumin-creatinine ratio (UACR) used to identify microalbuminuria have been based on studies that predicted risk in diabetic patients. Objective: To determine whether the relation between albuminuria and cardiovascular risk can be used to predict cardiovascular morbidity and mortality in hypertensive patients. Design: Multicenter cohort study derived from a randomized, controlled trial. Patients: 8206 patients with stage II or III hypertension randomly assigned to double-blind therapy with losartan or atenolol. Follow-up was 39 122 patient-years. Measurements: Renal glomerular permeability evaluated by UACR. Results: In nondiabetic hypertensive patients with left ventricular hypertrophy, the risk for the composite cardiovascular end point increased continuously as albuminuria increased (P < 0.001 for trend). There was no specific threshold for increased risk. For every 10-fold increase in UACR, hazard ratios in nondiabetic patients increased as follows: composite end point, by 57% (95% CI, 40.6% to 75.0%); cardiovascular mortality, by 97.7% (CI, 66.5% to 235%); all-cause mortality, by 75.2% (CI, 54.0% to 99.4%); stroke, by 51.0% (CI, 28.8% to 76.9%); and myocardial infarction, by 45% (CI, 19.9% to 75.4%) (P < 0.001 for all comparisons). Values were similar in diabetic patients, although for myocardial infarction the trend was weaker and not significant. Conclusion: Increased UACR resulted in increasing risk for cardiovascular morbidity and mortality among hypertensive patients with left ventricular hypertrophy. We found no thresholds or plateaus. Risk increases at much lower UACR values than has been reported among diabetic patients.