We evaluated the 22-year results of initial coronary artery bypass surgery with saphenous vein grafts compared with initial medical therapy on survival, incidence of myocardial infarction, reoperation, and symptomatic status in 686 patients (average age 51) with stable angina in the Veterans Affairs Cooperative Study of Coronary Artery Bypass Surgery. Between 1972 and 1974, 354 patients were assigned to medical treatment and 332 to surgical revascularization. In the surgical cohort, 312 patients underwent operation (operative mortality 5.8%) and 25% subsequently underwent repeat operation (operative mortality 10.3%). In the medical cohort, 160 patients crossed over to surgery (operative mortality 4.4%) and 21% of these patients had reoperation (operative mortality 9.1%). Neither crossover nor reoperation was predictable by angiographic or clinical risk factors measured at baseline. The overall 22-year cumulative survival rates were 25% and 20% in the medical and surgical cohorts (p = 0.24). Corresponding rates in low-risk patients who had 1 or 2 vessels diseased, or 3 vessels diseased with normal left ventricular function were 31% and 24% (p = 0.024). Although significant at 10 years, there was also no long-term survival benefit for high-risk patients assigned to bypass surgery. The probabilities of remaining free of myocardial infarction and of being alive without infarction were significantly higher with initial medical therapy, 57% versus 41% (p = 0.02) and 18% versus 11% (p = 0.0031), respectively. This trial provides strong evidence that initial bypass surgery did not improve survival for low-risk patients, and that it did not reduce the overall risk of myocardial infarction. Although there was an early survival benefit with surgery in high-risk patients (up to a decade), long-term survival rates became comparable in both treatment groups. In total, there were twice as many bypass procedures performed in the group assigned to surgery without any long-term survival or symptomatic benefit.