From 1988 through 1991, 1663 patients underwent a first reoperation for isolated coronary bypass grafting with 62 (3.7%) in-hospital deaths. At the primary operation, 575 patients had received at least one internal thoracic artery graft and 489 patients had at least one patent internal thoracic artery graft present at the time of reoperation. At reoperation, 1014 patients received at least one internal thoracic artery graft, 10 received an inferior epigastric graft, and 37 received a gastroepiploic graft. Of 489 patients with patent internal thoracic artery grafts at reoperation, the internal thoracic artery was damaged in 17 (3.5%); of 428 patients with a patent internal thoracic artery graft to the left anterior descending coronary artery, 14 (3.3%) had graft damage necessitating regrafting. All patients with damaged internal thoracic arteries survived. Multivariate testing of variables for their association with in-hospital mortality identified no internal thoracic artery graft at either primary surgery or reoperation (p < 0.0001), a history of congestive heart failure (p < 0.0001), advancing age (p = 0.018), female gender (p = 0.029), and emergency operation (p = 0.01) as factors linked to increased risk. Left ventricular function, left main stenosis, extent of native coronary atherosclerosis, and the interval between operations did not influence mortality. Furthermore, the presence of an atherosclerotic vein graft to the left anterior descending coronary artery a factor shown to increase in-hospital risk in previous studies did not increase risk during these years. We attribute the observation that patent internal thoracic artery and atherosclerotic vein grafts do not appear to be factors specifically increasing the risk of reoperation to the use of retrograde cardioplegic solution and increased surgical experience. The use of internal thoracic artery grafts at a primary operation does not increase the risk of a reoperation, and the use of internal thoracic artery grafts at reoperation does not increase in-hospital morbidity or mortality.