The impact of microalbuminuria and macroalbuminuria on mortality was evaluated prospectively in 328 Caucasian patients with non-insulin-dependent diabetes mellitus (NIDDM) followed for five years. One hundred and ninety-one patients with normoalbuminuria (albumin excretion rate (AER) < 30 mg/24 h), 86 patients with microalbuminuria (AER 30-299 mg/24 h), and 51 patients with macroalbuminuria (AER > or = 300 mg/24 h) all less than 66 years old at start of the study were followed from 1987 until death or until 1 January 1993. Eight percent of patients with normoalbuminuria, 20% of patients with microalbuminuria, and 35% of patients with macroalbuminuria had died, predominantly from cardiovascular disease. Significant predictors of all-cause mortality included preexisting coronary heart disease, AER, HbA1c level and age. Significant predictors of cardiovascular mortality included preexisting coronary heart disease, macroalbuminuria, HbA1c level and systolic blood pressure. Abnormally elevated urinary albumin excretion and poor glycaemic control indicate a substantially increased all-cause, mainly cardiovascular, mortality risk in NIDDM patients.