This study was designed to evaluate the late changes of coronary bypass grafts in 60 patients who had undergone coronary bypass surgery and postoperative angiography in the period from 1994 to 1999. Angiography was performed at mean intervals of 84 months and a total of 134 grafts and 162 anastomoses were visualized. The Left internal thoracic artery and saphenous vein had a patency of 85% and 82%, there was not statistically significant. In this series, late graft function did not relate to the site of implantation, that was mainly due to excellent results of saphenous vein grafts. With increasing proximal stenosis severity (under 75% versus over 90%), there was an increase in patency rates and this relationship was statistically significant (p=0.0005). That was why about 20% of the grafts to moderately stenotic target vessels had occluded within 1 month after surgery. Ten patients among these 60 had cardiac symptoms, 6 were due to graft failure and the other 4 were due to new lesions in the right coronary artery. In the other 12 patients new coronary artery lesions without cardiac symptoms had been detected. Periodic coronary examinations should be recommended for the patients after surgery, regardless of the absence of symptoms.