Insertion/deletion (I/D) polymorphism of the angiotensin I-converting enzyme (ACE) gene was studied in healthy individuals (N = 168) and in patients with myocardial infarction (N = 31), hypertrophic cardiomyopathy (N = 14), or arterial hypertension (N = 26) from Moscow and Moscow Region. Significant deviations: decreased homozygosity in the deletion-carrying allele (D/D, 19.2%) and increased heterozygosity (I/D, 65.4%), were only found in patients with arterial hypertension as compared with controls of the same sex and age (45.2% and 38.1%, respectively). A similar tendency was detected in postinfarction patients and those with cardiomyopathy. The paradoxical decrease in the frequency of D/D (an independent genetic marker of predisposition to cardiovascular diseases) can be explained by the age composition of the tested sample, because this genotype is associated with higher risk of premature death in older patients with hypertension and cardiopathies. The association of the ACE gene with angiopathies and the involvement of both genetic and nongenetic factors in the development of the above diseases were assumed.