Abstract: Objective　To investigate the significance of detecting homocysteine（Hcy） by enzyme transition method and the early diagnostic significance of Hcy to coronary heart disease. Methods　The enzyme transition method for detecting Hcy was evaluated by methodology for precision，linearity，interference，recovery and sensitivity tests，and was compared to high performance liquid chromatography（HPLC） method. The levels of Hcy among 60 coronary heart disease patients，55 healthy controls and 54 patient controls with normal blood lipid and glucose（Glu） levels and atherosclerosis family medical history were detected by enzyme transition method，and the levels of Glu，total cholesterol（TC） and triglyceride（TG） were detected. Results　The within-run imprecisions（CV） were 1.98% and 2.34% respectively. The between-run CV were 2.13% and 1.87% respectively. The interday CV were 2.47% and 1.33% respectively. The total CV were 3.85% and 2.41% respectively. There was a good linear relationship between 2-80 μmol/L（r²＝0.987 4）. Almost no significant interference can be observed in the enzyme transition method to detect Hcy of TG＜20 mmol/L，total bilirubin（TBil） ＜300 μmol/L and hemoglobin（Hb）＜10 g/L（P＞0.05）. The recovery rate was 98.9%-102.4%. The sensitivity was 0.27μmol/L. There was a good correlation between the enzyme transition method and HPLC method by linear-correlated analysis（r＝0.935 2），and there was no significant difference between the 2 methods（P＞0.05）. The positive correlation of Hcy with Glu and TG（r＝0.447 and 0.426，P＜0.01），and no correlation between Hcy and TC were shown（r＝0.146，P＞0.05）. The levels of Hcy in coronary heart disease group and patient control group were higher than those in healthy control group（P＜0.01）. The levels of TG and Glu in coronary heart disease group were higher than those in patient control group and healthy control group（P＜0.01）. Conclusions　Enzyme transition method is suitable for clinical laboratory with the advantages of good precision，high sensitivity，wide linear range，good anti-interference ability and accurate results. It has a significance for the early diagnosis of coronary heart disease when the level of Hcy rises.

Key words: Homocysteine, Coronary heart disease, Enzyme transition method, Methodology evaluation