Some patients with essential hypertension manifest increased urinary albumin excretion (UAE). Hypertensive patients with microalbuminuria manifest abnormal circadian variation of blood pressure, increased serum levels of LDL-cholesterol and lipoprotein(a), a greater rise of serum insulin in response to an oral glucose tolerance test, and greater thickness of the carotid artery than patients without microalbuminuria. A 7 year follow-up of 141 hypertensive patients, 54 with microalbuminuria and 87 without microalbuminuria, we observed 12 cardiovascular events in patients with microalbuminuria and only 2 events in the patients with normal urine albumin excretion (P < 0.0002). Creatinine clearance decreased more in patients with microalbuminuria than in those with normal UAE. In conclusion, hypertensive individuals with microalbuminuria manifest a greater incidence of cardiovascular events and more decline in renal function than patients with normal UAE. We propose that measurements of UAE may be a useful marker for cardiovascular risk in patients with essential hypertension.