The aim of this study was to study the relationship between plasma homocysteine (Hcy), folic acid, vitamin B₁₂ and early coronary artery disease (early-CAD) and high coronary risk factors. The plasma Hcy levels of 58 cases with early-CAD and 31 subjects without CAD were measured using high-performance liquid chromatography (HPLC) with fluorescence detection. Plasma folic acid and Vitamin B₁₂ levels were measured with radioassay method. The plasma Hcy level was significantly higher in the early-CAD patients than in the controls [ (13.7 ± 5.1) μmol/L vs (10.3 ± 5.7) μmol/L]. The plasma folic acid and Vitamin B₁₂ levels were significantly lower in the early-CAD patients than in the controls. The plasma Hcy level was higher in patients with more than 3 risk factors of CAD than in patients with 1 or 2 risk factors and in the controls [ (17.3 ± 5.1) μmol/L vs (12.9 ± 4.8) μmol/L, (7.8 ± 2.5) μmol/L]. Other than gender, all classical coronary risk factors were related to the elevated Hcy level. Hcy levels were elevated in patients with early-CAD and with high risk factors. Hyperhomocysteinemia plays an important role in the pathogenesis of CAD.