An insertion/deletion (I/D) polymorphism of the angiotensin converting enzyme (ACE) gene has been associated with increased risk for myocardial infarction, cardiomyopathy, carotid thickening, and cardiac hypertrophy. However, a conclusive agreement about the role of ACE genotype in the genetics of cardiovascular disease has not yet been reached. This study was undertaken to investigate the relationship of the I/D polymorphism of the ACE gene with carotid intima-media thickness (IMT) and left ventricular mass (LVM) in 175 Chinese patients with mild-to-moderate hypertension. The I/D genotypes were detected by the polymerase chain reaction using primers flanking the polymorphic region in intron 16 of the ACE gene. The IMT was measured in the common carotid and carotid bifurcation by B-mode ultrasound. The LVM was calculated with M-mode echocardiographic measures of the left ventricle. Patients with the DD genotype (n = 41) showed significant greater carotid IMT (1.593 +/- 0.879 v 1.309 +/- 0.703 and 1.171 +/- 0.583 mm, P = .01) but insignificant higher LVM index (123.8 +/- 36.6 v 123.7 +/- 37.4 and 118.2 +/- 33.0 g/m2, P = .61) than did those with the DI (n = 69) and II (n = 65) genotypes. The deletion polymorphism of the ACE gene (P = .04) was a significant predictor for carotid IMT on multiple regression analysis, controlling all the potential confounding factors including age (P = .001), systolic blood pressure (P = .09), smoking (P = .08), and plasma tissue plasminogen activator antigen (P = .03), but the LVM correlated only with age (P = .02), sex (P < .001), and body mass index (P < .001). These results indicated that the DD genotype of the ACE gene could be considered a risk factor for the development of early atherosclerosis in carotid arteries but not for left ventricular hypertrophy in the hypertensive population.