Microalbuminuria is associated with an increased risk of cardiovascular and renal disease in patients with diabetes and hypertension. The role of microalbuminuria as a predictor of coronary heart disease (CHD) has not been examined in large general-population cohorts, and its prognostic significance in persons with established CHD is uncertain. The authors examined the relation between microalbuminuria and incident CHD (1993-2002) in a population-based British cohort of 22,368 men and women aged 40-79 years without prevalent baseline CHD and evaluated its prognostic significance in 1,596 participants with baseline CHD. Participants were members of the Norfolk, United Kingdom, component of the European Prospective Investigation into Cancer and Nutrition (the EPIC-Norfolk Study). At baseline, participants were categorized into normoalbuminuria, microalbuminuria, and macroalbuminuria groups. During an average of 6.4 years of follow-up, 800 primary CHD events were registered. The age-adjusted incidence of CHD increased significantly across ordered categories of albuminuria (4.3, 4.4, and 5.6/1,000 person-years across tertiles of normoalbuminuria, 7.1/1,000 person-years for microalbuminuria, and 12.2/1,000 person-years for macroalbuminuria; p for trend < 0.001). The multivariate hazard ratio for incident primary CHD was 1.36 (95% confidence interval (CI): 1.12, 1.64) for microalbuminuria and 1.59 (95% CI: 1.10, 2.37) for macroalbuminuria. Among participants with established baseline CHD, the independent risk of all-cause mortality associated with microalbuminuria was 1.61 (95% CI: 1.19, 2.07). Microalbuminuria may be useful in identifying persons at increased risk of CHD and subsequent death in the general population.