Background & Aim: The most important cause of mortality in developing countries is coronary artery diseases(CAD). From ethiological point of view, CAD is multifactorial. In this study, some involved important factors were evaluated. Patients and Methods: In this cross-sectional study, 94 normal controls and 106 cases with 50% angiographically proved coronary stenosis who had referred to Tehran Shahid Rajaii Heart Hospital were selected and investigated inregard to levels of TG, HDL-C, VLDL-C, Apo A1, Apo B100, ACE activity and BMI in the both groups. Results: The results showed significant changes in the serum ACE activity, HDL-C, TG, VLDL-C, APO A1 and BMI compared with control group. Furthermore, multiple linear regression analysis showed odds ratios for ACE activity, cholesterol, HDL-C and VLDL-C as 1.08, 1.24, 1.05 and 0.68 respectively. However, the ACE activity had no correlation with the other studied factors. Conclusion: Increase of serum ACE may be an independent factor in the incidence of CAD and its inhibition may delay the atherosclerosis process.