To examine whether microalbuminuria is a marker of cardiovascular disease in treated hypertensive men without diabetes mellitus at high coronary risk and to examine the associations between microalbuminuria and recognized cardiovascular risk factors. Cross-sectional study. Outpatient clinic in city hospital. Three hundred and thirty-three treated hypertensive men, aged 50-72 years, either with a serum cholesterol of > or = 6.5 mmol/l or smokers, or both. The patients were recruited mainly from a population-based sample of hypertensive men. Patients with diabetes mellitus or overnight urinary albumin excretion of > 100 mg/12 h were excluded from the analyses. Overnight urinary albumin excretion, prevalence of microalbuminuria (defined as 17-100 mg/12 h) and organ damage (cardiovascular events or major electrocardiogram changes, or both), various well-established risk factor levels, blood glucose and plasma insulin responses to an oral glucose tolerance test. Microalbuminuria was found in 25% of the cohort. Among microalbuminuric patients, organ damage was significantly more common (47.6%) than in the normoalbuminuric group (30.9%). However, the sensitivity and specificity of microalbuminuria as a marker of organ damage were only 34 and 80%, respectively. Microalbuminuria was significantly related to body mass index and waist:hip ratio, age and plasma insulin during oral glucose tolerance testing. These relationships also persisted after adjustment for treatment with thiazides or beta-blockers. In treated hypertensive men without diabetes mellitus, microalbuminuria was associated with factors known to be related to insulin resistance. It had a low sensitivity as a marker of concomitant cardiovascular disease.