Recently, homocysteine and new inflamatory biomarkers are demonstrated to be involved in cardiovascular diseases. These risk factors are not well studied in acute coronary syndrome. We investigated the distribution of homocysteine and inflammatory markers in patients with acute coronary syndrome and evaluated the association between these parameters and severity of the disease. One hundred and twenty-two patients with acute coronary syndrome were recruited in the cardiac intensive unit care of military hospital of Tunis. Classic risk factors, lipid parameters, total homocysteine, HsCRP, IL-6 and TNFα were determined for all participants. We investigated the distribution of these parameters according to the number of diseased vessels in patients with acute coronary syndrome. Patients with three affected vessels showed significant elevated homocysteine, HsCRP, IL-6, TNF-α, total cholesterol, LDL-cholesterol and Lp (a) compared to those with one and those with two affected vessels. Homocysteine (OR = 1.14; 95%IC: 1.04-1.25; P = 0.006), TNF-α (OR = 1.27; 95%IC: 1.13-1.44; P = 10(-3)), HsCRP (OR = 1.09; 95%IC:1.03-1.16; P = 0.005) and IL-6 (OR = 1.15; 95%IC: 1.06-1.25; P = 0.001) were significant predictors of severity of the disease. We conclude that homocysteine and inflammatory biomarkers appear to enhance the degree of affected arteries and so the severity of coronary artery disease.