To investigate a possible association of ABO blood groups with coronary artery disease in well-documented patients, we designed a cross-sectional study of 2026 patients, known case of coronary artery disease in angiography, who underwent coronary artery bypass graft at Tehran Heart Center, with regard to coronary artery disease major risk factors as well as ABO blood groups. Analysis did not show any significant difference between the frequency of ABO blood groups in coronary artery disease patients compared to the Iranian general population. In addition, frequency of cardiac risk factors was similar in coronary artery disease patients with different blood groups. Therefore, these finding suggest that there is no correlation between various ABO blood groups and development of coronary artery disease. Moreover, the prevalence of major risk factors was equal in patients with different blood groups, and blood groups had no impact on development of premature coronary artery disease in individual subjects.