There is limited information about the effect of preoperative continuation of aspirin therapy on perioperative graft patency in patients undergoing off-pump coronary artery bypass (OPCAB). We sought to evaluate the effect of preoperative continuation of aspirin therapy on perioperative graft patency after OPCAB. Using retrospectively collected data from 582 consecutive patients undergoing first-time isolated OPCAB by a single surgeon at Fuwai Hospital from October 2009 through September 2012, we evaluated the association between aspirin (100 mg daily) preceding OPCAB and the risk of adverse in-hospital postoperative events. The primary outcomes were in-hospital mortality and graft patency. The secondary outcome measures were hemorrhage-related outcomes (reexploration rate, blood transfusions, perioperative drainage loss). There was no death in the postoperative hospitalization period. Patients receiving preoperative continuation of aspirin therapy (n = 400) had significantly higher postoperative saphenous venous graft patency than did those not receiving preoperative aspirin [98.2% vs 96.1%, p = 0.02]. Multivariate analysis indicated that preoperative discontinuation of aspirin therapy significantly increased the risk of occlusion of saphenous venous graft (odds ratio, 2.193; 95% confidence interval, 1.023 to 4.701, p = 0.043). No significant differences between the two groups were observed in perioperative bleeding risks, including chest tube drainage, blood product transfusion, and reoperation for bleeding. This study indicates that preoperative continuation of aspirin therapy may improve perioperative saphenous vein graft patency after OPCAB without increasing the risk of perioperative bleeding.