Objectives: Our objectives were to characterize the outcome of coronary artery bypass grafting in patients with previous mediastinal radiation therapy and to identify special features of this condition that relate to surgical management. Patients and methods: We conducted a retrospective review of 47 patients (28 women, 19 men) with a mean age of 63.5 ± 12.8 years (range 31.0-82.9 years) from 1976 through December 1996 undergoing coronary artery bypass graft after mediastinal radiation therapy. Results: The mean interval between mediastinal radiation therapy and coronary artery bypass grafting was 15.1 ± 9.8 years (range 1.1-37.8 years). In the 44 patients with isolated coronary surgery, operative mortality was 3 patients (6.8%). Sternal wound infection occurred in 3 patients (6.8%). Actuarial survival at 1 and 5 years was 87.2% ± 4.9% and 71.6% ± 7.1%, respectively. Total follow-up was 293.7 patient-years (mean 6.2 ± 5.1 years). There were 17 late deaths (malignancy, n = 7; heart failure, n = 6; stroke, n = 1; other noncardiac causes, n = 2; and sudden death, n = 1). Twelve of 43 discharged patients had the development of valvular disease demonstrated by follow-up echocardiography. Conclusions: The early results of coronary artery bypass grafting for the treatment of ischemic heart disease after mediastinal radiation therapy are good. Late survival, however, is limited by malignancy, either recurrent or new, and the development of heart failure. Inasmuch as 25 other patients after radiation therapy required concomitant valve surgery and 12 of 43 (28%) discharged patients had later development of valvular disease, with 2 requiring reoperation, careful assessment of any valvular lesion is important during the initial coronary artery bypass grafting. Careful follow- up, including regular echocardiographic screening, is recommended in this patient population.