BACKGROUND: Outcome after coronary artery bypass grafting is usually evaluated by exercise stress testing. Increased exercise capacity and reduced angina pectoris have been equated with improved quality of life, but this represents a limited view. OBJECTIVE: To prospectively evaluate the effects of coronary artery bypass grafting on quality of life and exercise capacity and their interrelationship. METHODS: In a consecutive series of patients (N = 2365) who underwent coronary artery bypass grafting, we administered a questionnaire to assess quality of life before and 2 years after surgery. A standardized exercise test was performed during the year before surgery and 2 years after. A preoperative exercise test was performed by 726 patients. Among these patients, 462 completed a quality-of-life questionnaire preoperatively and 578 did so postoperatively. Preoperative and postoperative exercise tests were obtained from 362 patients. RESULTS: The improvement in quality of life was related to the severity of preoperative angina (P < .001) and female sex (P = .004) and was inversely related to preoperative exercise performance (P = .04). The improvement in exercise capacity was greater among men (P < .001) and was inversely related to preoperative exercise capacity (P < .001). CONCLUSIONS: The greatest improvement in quality of life after coronary artery bypass grafting appeared in those patients with the most impaired exercise capacity, those with the most severe angina pectoris, and women. Improvement in exercise capacity was greatest in patients with the poorest preoperative exercise capacity and in men. These findings indicate that exercise testing is of limited value as a measure of quality of life and that assessment by a questionnaire has a complementary place.