Abstract: Objective To compare the effect of different surgical procedures on graft blood flow in patients with left main coronary artery lesion. Methods One hundred and thirty-two patients with left main coronary artery lesion(98 males and 34 females) aged 63.5±8.6 years,who underwent operation in our hospital from January 2010 to December 2011,were divided into extracorporeal coronary artery bypass grafting group(extracorporeal circulation group,n=70) and non-extracorporeal coronary artery bypass grafting group(non-extracorporeal circulation group,n=62).A total of 219 grafts were bypassed,including 70 grafts for left internal mammary artery(LIMA) and 149 grafts for saphenous vein(SV) in extracorporeal circulation group.A total of 181 grafts were bypassed in non-extracorporeal circulation group,including 62 for LIMA and 119 for SV.Intra-operative blood flow volume,pulsation index(PI),and blood flow waveform of the patients were measured with a transit-time flow meter. Results No significant difference was found in the general data between the two groups before operation.The mean blood flow in LIMA-descending anterior branch graft and the PI were(27.3±16.5)ml/min,(27.7±18.7)ml/min and 3.1±1.6,3.0±1.8,respectively,the mean blood flow in SV-circumflex artery branch graft and the PI were(37.3±3.4)ml/min,(35.0±5.6)ml/min(P=0.086) and 2.9±1.5,3.0±1.7(P=0.675),respectively,in extracorporeal circulation group and non-extracorporeal circulation group(P>0.05). Conclusion Both extracorporeal coronary artery bypass grafting and non-extracorporeal coronary artery bypass grafting have no effect on grafted blood vessels and anastomotic stoma in patients with left main coronary lesion.