Although successful dilatation of a target lesion by means of percutaneous transluminal coronary angioplasty (PTCA) can be attained as frequently in elderly as in younger patients, elderly patients have a higher risk of complications. Furthermore, cohorts of patients older than 75 years and undergoing PTCA include more women and more cases of unstable angina, factors that increase the risk of complications. Included in this analysis of 3199 PTCAs performed between January 1991 and September 1992 were 474 (14.8%) patients who were > or = 75 years old. Age was an independent risk factor for death, acute myocardial infarction, need for transfusion, and need for arterial repair after PTCA. The frequency of successful dilatation of individual lesions, emergency coronary bypass surgery, or repeated PTCA of the same lesion was not related to age. In previous studies no association has been demonstrated between age and increased risk of in-hospital reclosure. The presence of more severe coronary disease and of the greater frequency of coexisting morbid conditions makes elderly patients less able to tolerate unsuccessful or complicated PTCA.