Familial clustering of microalbuminuria with cardiovascular disease suggests a possible common genetic antecedent. We have tested the hypothesis that the angiotensin-converting enzyme (ACE) DD genotype and the angiotensin II type I receptor (AT1R) gene C allele represent the common link between microalbuminuria and coronary heart disease. The frequency of polymorphisms of the ACE and AT1R genes were investigated in 509 nondiabetic white subjects and in 86 non-insulin-dependent diabetic white patients. There was no significant difference in albumin excretion rate between the genotypes in nondiabetic subjects on either a daytime or an overnight sample or in diabetic subjects expressed as a normalized albumin concentration on an untimed morning urine collection. We have found no evidence for an association between polymorphism of the ACE or AT1R genes and microalbuminuria in two groups of subjects without insulin-dependent diabetes.