Angiotensin II is the major effector molecule of renin-angiotensin system; its production can be conveniently interrupted by angiotensin-converting enzyme (ACE). Typical plasma levels of ACE accompany the I/D polymorphism; however, a controversy exists as to whether the DD genotype of the ACE polymorphism affects the risk for the development of coronary artery disease (CAD) and to what extent the ACE polymorphism is associated with CAD in different populations. We compared the I/D polymorphism in 212 CAD patients younger than 50 years with 165 healthy control individuals. They were all from the Tuzla region in Bosnia and Herzegovina. Patients with CAD had a higher prevalence of the DD genotype (36.3%) than controls (25.6%). The odds ratio for the ACE DD genotype in CAD patients was 1.7 (95% confidence interval 1.0-2.7; p < 0.05). We may conclude that the D/D genotype of the ACE gene polymorphism is associated with an increased risk for CAD in the Bosnian population.