We treated 162 patients by isolated CABG with a left internal thoracic artery (LITA) anastomosed to the left anterior descending artery and a radial artery anastomosed to the circumflex artery between August 1996 and December 2002. Late angiograms were performed 6 to 65 months (21.7±15.8) after the operation. The purpose of this study was to compare midterm results of radial arteries anastomosed to the side wall of LITA (group Y) with those anastomosed to the aorta (group AC). There were no operative deaths in either group and no difference in the postoperative complication rate including cerebral infarction. The early patency of group Y was lower than that of group AC (group AC: 97.8%, group Y: 87.1%, p=0.017), and also the late patency of group Y was significantly lower than that of group AC (group AC: 90.9%, group Y: 36.4%, p=0.0008). All of the early patent radial artery grafts in group AC were patent on late angiograms, but 3 of the 25 anastomoses in group Y which were clearly patent on early angiograms later showed a string sign later. When using a radial artery graft in circumflex artery territory, we recommend an aorto-coronary bypass graft rather than Y-graft.