['Angiotensin II is produced primarily by angiotensin I-converting enzyme (ACE) within atherosclerotic lesions and ACE level in plaques correlates with the severity of vessel wall damage. Therefore, we investigated the possible association of ACE gene insertion/deletion (I/D) polymorphism and the severity of atherosclerosis, estimated on the basis of the number of coronary stenoses and critical arterial occlusions observed during coronary angiography.', 'The study cohort included 172 patients with angiographically confirmed premature coronary artery disease. The ACE gene I/D polymorphism was genotyped using a PCR method.', 'The frequencies of DD genotype, D allele carrier-state (DD+ID genotypes) and the D allele increased with the number of stenoses in coronary vessels. D allele carriers (DD+ID genotypes) were more frequent in the subgroup of patients with stenoses in at least four coronary vessels than in other patients including subjects with one-, two- and three-vessel disease (97.4% vs. 74.4%, OR=13.05, 95% CI: 1.81-100.00, chi2=9.84, p=0.0017). Furthermore, the D allele was significantly more frequent in patients with critical arterial occlusions (>90%) than in subjects without critical stenoses (61.1% vs. 49.3%, chi2=9.84, p=0.023).'] Is the D allele of angiotensin I-converting enzyme gene insertion/deletion polymorphism associated with the severity of atherosclerosis?