The following effects in treatment of coronary artery disease are desired: 1. Elimination or improvement of angina. 2. Improvement of physical capacity. 3. Prevention of imminent complications (myocardial infarct, cardiac arrhythmias, heart failure, embolism). 4. Elimination or diminuation of risk factors. 5. Prolongation of life. - In a critical survey concerning long-term studies of patients with aorto-coronary bypass or medical treatment in the literature subtile lists of indications for surgical and conservative treatment are put up (Table II and III), illustrated by case reports. - Useful criteria for diagnosis, follow-up, and prognosis are selective coronary angiography, ventriculography as well as determination of the coronary reserve (Argon Method). Indication for aorto-coronary bypass and resection of myocardial aneurysms are presented. Principles of medical treatment are: 1. Diminuation of myocardial oxygen requirement (release of pressure, economisation of work load, recompensation, regulation of arrhythmias) and 2. improvement of myocardial oxygen supply (Diminuation of coronary perfusion resistance including prevention and treatment of atherosclerosis). Indication for various medications are discussed (nitrites, beta-adrenergic blocking agents and antihypertensive drugs, glycosides, medication for arrhythmias, coronary dilatators, anticoagulants, and lipotropic substances). Their mode of action is debated and documented by own results. Present possibilities and limits in treatment of coronary artery disease are presented.