Coronary ostial stenosis as a complication of atherosclerosis is a rarely emphasized angiographic finding. Its recognition is important because of the adverse prognosis of left main stenosis and the inherent risks during catheterization of these patients. Recently 3 patients were identified with left coronary ostial stenosis. A clinical picture emerged during coronary angiography characterized by an abrupt fall in catheter tip pressure associated with symptoms of dyspnea and chest pain. Contrast media injections into the sinus of Valsalva, in right anterior oblique and left anterior oblique projections, revealed characteristic angiographic changes.