Coronary artery disease (CAD) is the leading cause of death in the world and in our country. CAD, which is sometimes a fatal and often chronic disease, is a social problem with both a serious economic burden and negative effects on the quality of life. The statistical studies conducted since the discovery of blood groups suggest that there is a positive correlation with coronary artery disease and blood group, especially group A. In the studies conducted on this subject, the lowest CAD risk is observed in people with O blood group. Although the mechanism of the relationship is not fully elucidated, the findings indicate the WCAA gene, the Willebrand Factor (vWF), Factor VIII, and the ABCA2 gene responsible for cholesterol homeostasis in the coagulation mechanism. The studies conducted on this subject in our country are insufficient. Therefore, it was aimed to retrospectively examine the association of MI cases with blood groups in order to determine the association of MI and CAD cases with blood groups. According to the results of the study, the blood group A and B are more common in the MI and CAD patients and less in the O group. This value was found to be 46% for group A, 40% for normal population, 20% for B group, 17% for normal population and 25% for patients and 28% for normal group.