We performed this study to determine if bilateral internal thoracic artery grafts provide greater benefit than single internal thoracic artery grafts. Six hundred ninety-four consecutive patients who received 2 coronary grafts in a single operation during 1983-1989 were given 10 years of follow-up and then analyzed retrospectively. Group 1 (n=382) received 2 internal thoracic artery grafts, Group 2 (n= 139) received 1 internal thoracic artery graft and 1 saphenous vein graft, and Group 3 (n= 173) received 2 saphenous vein grafts. Patient demographics, preoperative angiographic findings, and operative indications were the same. Hospital mortality rates were 2.6%, 2.2%, and 2.3%, respectively. Hemorrhage, sternal wound infection, mediastinitis, sternal dehiscence, and prolonged ventilatory support showed no group differences. Follow-up over 10 years was complete in 677 survivors. Mortality rates during follow-up were 1.8%, 2.9%, and 4.7%, respectively. Cardiac-related mortality rates were 71%, 75%, and 88%, respectively (Group 1 vs Group 3, P=0.0412). Ten-year survival was better for Group 1 than for Groups 2 and 3 (P=0.0356 and P <0.0001). Cardiac-event-free survival at 10 years was 93% in Group 1, 84% in Group 2, and 74% in Group 3 (all P <0.0001). The use of 2 internal thoracic artery grafts resulted in significantly lower risk of cardiac death and re-intervention, compared with the use of 1 internal thoracic artery, which in turn was superior to the use of vein grafts. Use of double internal thoracic arteries did not increase postoperative complications.