Acute gastrointestinal (GI) illnesses are unusual but potentially fatal complications following cardiac transplantation. A retrospective study was performed to analyze the frequency, etiology, and severity of GI complications and the potential impact of early diagnosis and prompt surgical intervention when appropriate. Between 1981 and July 1, 1988, 31 GI complications (pancreatic, 6; colonic, 6; gastroduodenal, 6; biliary, 5; esophageal, 3; appendiceal, 2; hernia, 2; and splenic, 1) occurred in 26 patients undergoing 32 cardiac transplants. Complications were most common (14 of 31 patients, 45%) within the first 30 days after transplantation. Seventeen GI complications were treated medically (2 deaths), 2 with elective surgery and 12 with emergent operations (3 deaths). The overall mortality rate was 16%. All patients who underwent emergent operations within 3 days of onset of symptoms survived; the mean interval of onset between symptoms and operation in the nonsurvivors was 10 +/- 3.8 days. We infer that among patients requiring urgent surgical intervention, successful outcome is enhanced by intense surveillance for early symptoms, prompt diagnostic evaluation, and early surgical intervention.