BACKGROUND: The role of novel biomarkers like homocystein as a risk factor of coronary artery disease (CAD) is being increasingly recognized. There is a marked geographical variation in plasma homocystein concentration. In spite of importance of hyperhomocysteinemia in CAD risk, there is a paucity of studies in Iran that evaluate it. Consequently, we evaluated the association between plasma total homocystein (tHcy) concentration and CAD risk in an Iranian population.METHODS: In a case-control study, we compared the level of tHcy of forty five patients with angiographically proved CAD with forty five age and gender matched subjects without CAD as control group. The patients with diabetes, hypertension, thyroid dysfunction, chronic renal failure, hyperlipidemia and obesity and other conventional CAD risk factors were excluded from the study. Plasma tHcy was measured using immunoturbidimetry. RESULTS: Homocystein level was higher in men than women (16.7 ± 5.2 versus 14.3 ± 3.9 micromol/lit, P = 0.019). CAD patients had higher mean plasma tHcy than control group (17.1 ± 5.3 versus 14.2 ± 3.8 micromol/lit, P = 0.004). CONCLUSION: This study denoted that high plasma homocystein concentration is associated with CAD risk in Iranian people. Keywords: Coronary Artery Disease, Homocystein, Iran.