The incidence of abdominal complications after cardiopulmonary bypass is low but associated with a high mortality. From January 1991 to October 1996, 4288 patients, of a mean age of 62.5 years, underwent open-heart surgery. Fifty-nine (1 of 4) of these patients developed early abdominal complications. These included 36% with a paralytic ileus, 21% with erosive gastritis, 18% with upper gastrointestinal haemorrhage, 12% with intestinal ischaemia, 5% with pseudo-obstruction of the colon, 6% with acute cholecystitis and 2% with acute pancreatitis. After coronary artery bypass grafting mean cardiopulmonary bypass time was 94.4 min. There were abdominal complications in 1.0% and one hospital death. After valve surgery and combined surgery the mean cardiopulmonary bypass time was 129 min. There were abdominal complications in 2.4% (alpha = 0.01) and seven deaths. Fourteen patients (24%) underwent abdominal operations: three had caecostomies for pseudo-obstruction of the colon, seven had a hemicolectomy, two had a cholecystectomy and two had resection of the ventricle. The hospital mortality rate was 13.5%. Abdominal complications were significantly more frequent after valve or combined operations of the coronaries and valves in comparison with isolated coronary artery bypass grafting. Cardiac operations with extended cardiovascular bypass time were more likely to produce abdominal complications.