BACKGROUND: Conventional coronary artery bypass grafting performed with the use of cardiopulmonary bypass is a well-validated treatment for patients with ischemic heart disease. Off-pump coronary artery bypass grafting (OPCAB) has been suggested to reduce the number of perioperative complications, especially in elderly patients. METHODS AND RESULTS: In a multicenter, randomized trial, we assigned 900 patients >70 years of age to conventional coronary artery bypass grafting or OPCAB surgery. After 30 days, a blinded end-point committee assessed whether a combined end point of death, stroke, or myocardial infarction had occurred. At baseline and 6 months postoperatively, self-assessed quality of life was measured with the Medical Outcomes Study Short Form-36 and EuroQol-5D questionnaires. A 6-month follow-up of mortality was performed through the Danish National Registry. The proportion of patients experiencing the combined end point within 30 days was 10.2% for conventional coronary artery bypass grafting and 10.7% for OPCAB. Implied risk difference of 0.4% (with a 95% confidence interval, -3.6 to 4.4) showed nonsignificance in a standard test for equality (P=0.83) and for noninferiority with an inferiority margin of 0.5% (P=0.49). At the 6-month follow-up, mortality was 4.7% compared with 4.2% (P=0.75). Both groups showed significant improvement in self-assessed health-related quality of life. CONCLUSIONS: Both conventional coronary artery bypass grafting and OPCAB are safe procedures that improved the quality of life when performed in elderly patients. No major differences in intermediate-term outcomes were found. However, the noninferiority of OPCAB with the prespecified margin could not be confirmed. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00123981.