G. Berton, R. Cordiano, R. Palmieri, F. Cucchini, R.DeToni and P. PalatiniAims Urinary albumin excretion increases during acute myocardial infarction but little is known on the prognostic significance and the pathophysiological mechanisms of microalbuminuria in this clinical setting. The primary aim of the study was to examine whether urinary albumin excretion has predictive power for 1-year mortality after acute myocardial infarction. A secondary objective was to gain insight into the pathophysiological mechanisms of increased urinary albumin in myocardial infarction.Methods and Results This is a prospective cohort study conducted in three coronary care units (Northeast Italy). Four hundred and thirty-two unselected, consecutively enrolled patients with acute myocardial infarction (66·3± 12·3 years of age) were studied. The incidence of mortality was related to the baseline urinary albumin:creatinine ratio. The best  cut-off  for  total  mortality   approximated   to 50 mg. g—1 on the first  day  after myocardial  infarction, 30 mg. g—1 on the third day, and to 20 mg . g—1 on the seventh day. At multivariable Cox analysis, the albumin:creatinine ratio was the strongest among several independent predictors of mortality (adjusted relative risks: 3·6 (95% CI, 2·1–6·2) on the first day, 4·9 (95% CI, 2·9–8·2) on the third day and 4·0 (95% CI, 2·3–6·8) on the seventh day). Independent determinants of urinary albumin were plasma aldosterone on the first day, and inflammatory markers on the third and seventh days.Conclusion Urinary albumin assessed in the first week after acute myocardial infarction is a strong prognostic marker for 1-year mortality.Eur Heart J. 2001; 22: 1466-75Key Words: acute myocardial infarction, microalbuminuria, albumin:creatinine ratio, aldosterone, inflammatory markers, prognosis