The three major randomized studies of medical vs surgical therapy in patients with coronary artery disease have had a major impact in the management of patients with this disease. For the most part, these multicenter trials have provided concordant information regarding the influence of surgery on survival in asymptomatic or mildly symptomatic patients. It has been demonstrated that coronary artery bypass surgery improves survival in patients with stenosis of the left main coronary artery. Bypass surgery probably should be performed in most patients with this lesion, although studies have identified low-risk subgroups in whom surgery may not improve survival. There are also concordant data that survival is not enhanced by surgery in mildly symptomatic patients with either one- or two-vessel disease. The important discrepancies regarding the role of surgery in three-vessel disease have been resolved to a major extent. Long-term follow-up studies in the Veterans Administration Cooperative Study and the Coronary Artery Surgery Study (CASS) demonstrate improved survival with surgical management in patients with three-vessel disease and left ventricular dysfunction. The remaining controversy regards management of patients with three-vessel disease and normal left ventricular function; this may be resolved by studies indicating that inducible left ventricular ischemia in patients with three-vessel disease and preserved left ventricular function at rest identifies patients at higher risk during medical management. Different proportions of such patients entered into the multicenter studies may explain the discordant results in three-vessel disease and normal left ventricular function reported by the European trial and CASS.(ABSTRACT TRUNCATED AT 250 WORDS)