We have tried to present a rational approach to selection of patients for coronary bypass surgery. An evaluation of both the anatomic and the clinical status of a patient in whom coronary arteriography has been performed, along with consideration of known results of medical and surgical forms of treatment of coronary artery disease in large series, determines which therapy is preferable. In all instances, the goal of treatment is threefold: relief of pain, preservation of myocardium and prolongation of life. In properly selected patients, pain can be relieved by surgery 90% of the time. Preservation of myocardium is a reality in some groups of patients treated surgically. Current data indicate that prolongation of life by coronary bypass surgery occurs in patients with left main coronary or triple-vessel disease, and as more data are collected, other subgroups may be included.