Abstract: Objective To investigate the relationship between graft flow and incidence of perioperative myocardial infarction (MI) in coronary artery bypass grafting (CABG). Methods Between January 2010 and June 2010, 58 consecutive patients with coronary artery disease who underwent offpump CABG in the First Hospital of Peking University were enrolled in this study. An anastomosis between left internal mammary arteries (LIMA) and left ant erior descending coronary artery (LAD) were performed. And saphenous vein (SV) graft s were used as bypass grafts. Graft flow was measured intraoperatively using a transi t time flowmeter, and the total graft flow of each patient was calculated as a parameter of myocardial revascularization. The 58 patients were divided into a MI group and a nonMI group retrospectively. There were 11 patients in the MI group, including 7 males and 4 females, with an average age of 67.4±10.3 years.There were 47 patients in the nonMI group, 38 males and 9 females, with a mean age of 633±99 years. The graft flow of the two groups was tested and compared, and the preoperative variables were compared. Results There was no statistically significant difference in operation time (205.4±59.6min versus 1834±32.4 min, t=1.691, P=0.096) between the two groups. Therewere also no statistical differences in the average number of grafts (3.00±1.00 branches versus 2.96±0.78 branches, t=0.154, P=0878) or LIMALAD flow (1540±11.37 ml/min versus 16.50±10.83 ml/min, t=0.301, P=0.764) between the two groups. However, a significant difference was found in the total graft flow between the two groups (41.03±19.50 ml/min versus 64.09±32.44 ml/min, t=2.254, P=0.028), with lower total graft flow in the MI group. Further analysis showed [CM(159mm]that a total graft flow lt;48.5ml/min was a risk factor for MI (odds ratio 4.706, 95% confidence interval 1.099 to 20.147). Conclusion Total graft flow could be used to predict the occurrence of perioperative myocardial ischemia, as there is a high probability of MI for patients with a total graft flow of less than 48.5 ml/min.