Simplified estimates of the potential patients eligible for coronary artery bypass surgery are presented. Various means of identification are discussed, as well as effects of two levels of stenosis. Although ultimate operability is not directly considered, the results demonstrate a substantial and growing pool of eligible patients. Data from the National Center for Health Statistics characterizes the trend toward more arteriograms and bypass procedures and more procedures being performed in smaller hospitals. Unexplained patterns exist with regard to racial and geographic differences. Factors that contribute to the increase of bypass procedures include more catheterizations being performed, declining mortality, the aging of the U.S. population, less reluctance to perform surgery, repeat operations, and increased availability of surgical teams and facilities. Factors discouraging an increase in the number of procedures include cost, equivocal results relative to increased survival in certain stages of disease, and improved alternative therapies.