Coronary artery disease (CAD) developed in 15 patients at a mean of 16 years (range 3 to 29) after chest irradiation. The mean dose of radiation was 42 +/- 7 grays; irradiation was performed for Hodgkin's disease in 9 patients, lymphoma in 2, breast carcinoma in 3 and cystic hygroma in 1 patient. Mean age was 48 years (range 26 to 63) at diagnosis of CAD; 4 patients were younger than 35 years. Nine were women. Ten presented with angina, 3 with acute myocardial infarction, 1 patient with syncope and 1 with dyspnea. Twelve had no more than 2 risk factors of atherosclerosis. At coronary angiography, 8 had at least 50% diameter narrowing of the left main coronary artery and 4 had severe ostial stenosis of the right coronary artery. Eight patients also had valvular heart disease, 4 pericardial disease and 4 complete heart block. Mean left ventricular ejection fraction was 67 +/- 11% (range 53 to 80%). Nine had undergone coronary artery bypass grafting, but surgery was difficult or impossible in 3 because of severe mediastinal and pericardial fibrosis. Radiation-associated CAD is characterized by a high incidence of left main and right ostial coronary disease and often occurs in women with relatively few conventional risk factors for CAD.