A total of 15 chronic renal failure patients on hemodialysis therapy underwent some kind of cardiovascular surgery between August 1984 and March 1993. Ten had a valve abnormality, and the remaining five had coronary artery disease. All of them were hemodialyzed the day before surgery and 24-48 h after the operation. Eleven recovered well after surgery, four died of septic shock: two of these were in septic shock prior to surgery; one was in acute congestive heart failure, and one was operated during an acute myocardial infarction. All operative deaths occurred in the patients who underwent non-elective surgery or were preoperatively in New Heart Association (NYHA) class IV. The factors having an impact on morbidity and mortality seem to be more related to the previous clinical situation and to the urgency of the operation than to the status of chronic renal failure. An early and adequate assessment of the candidates, when possible avoiding emergency surgery and acute left ventricular dysfunction, as well as careful management during cardiopulmonary bypass procedures (CPB) and the immediate post-surgical period will certainly improve the result of cardiac surgery in these patients, making it similar to those who are not in chronic renal failure.