Background: Cardiovascular disease is leading cause of mortality and morbidity in developed and developing countries. Metabolic syndrome (MS) is a risk factor for coronary artery disease (CAD). The effect of MS on angiographic severity of CAD is not well defined. The aim of this study was to examine the effect of MS on angiographic severity of CAD by using Gensini score. Methods: The total number of 1003 patients who underwent elective coronary angiography in catheter laboratory were included in the study. MS score based on National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III) criteria which ranged between zero and five were calculated for each subject. Gensini scores were determined by examining coronary angiograms of the patients. Results: The study population consisted of 634 (63%) male, and 369 (37%) female subjects. The mean age was 59 +/- 11. MS based on NCEP ATP III was present in 246 (25%) patients. CAD was present in 691 patients (69%). The median of Gensini score was five (0-192) in the total sample, 18 (1-192) in the patients with CAD and 25 (0-192) in the patients with MS. A positive correlation was found between MS score and Gensini score (r = 0.402, p < 0.001). Conclusions: In this study, it was determined that as the severity of MS increases, the angiographic severity of CAD increases as well. Besides, the most important factor on Gensini score was diabetes mellitus in male and hypertension in female subjects.