Microalbuminuria (MA) is a strong risk factor for subsequent chronic disease, both renal and coronary heart disease (CHD), in European origin populations, but CHD risks differ by ethnicity, and it was hypothesized that prevalence of MA and relations with CHD may also differ. Combined analyses of two population-based cohorts started in 1988 and consisted of 1460 Europeans (70% male), 946 South Asians (78% male), and 559 African Caribbeans (51% male) who resided in London and were aged 40 to 69. Baseline fasting blood, overnight urine collection, and clinical measurements were performed. Prevalent CHD was defined by clinical history or major electrocardiogram changes. Age-adjusted albumin excretion rates (AER; geometric means, mug/min) were significantly higher in African Caribbeans (men: 6.1, 95% confidence interval [CI] 5.5 to 6.7; women: 5.7, 95% CI 5.2 to 6.2) than in South Asians (men: 4.3, 95% CI 4.0 to 4.5; women 3.4, 95% CI 3.0 to 3.8) and Europeans (men: 4.5, 95% CI 4.3 to 4.8; women: 3.3, 95% CI 3.1 to 3.6). MA was associated with both prevalent CHD and CHD mortality in South Asian men (hazard ratio 2.5; 95% CI 1.3 to 4.8) and in European women (hazard ratio 13.0; 95% CI 2.6 to 64.2) but not in any other group. Greater AER in African Caribbeans and the absence of association with CHD contrast with lower AER in South Asian men and European women, both strongly associated with CHD prevalence and mortality. These differences suggest that the pathogenesis of kidney disease and its link with CHD differ by ethnicity and gender.