The treatment of acute leukemia in childhood has been increasingly successful. Infectious complications are the major cause of morbidity and mortality among these patients receiving aggressive chemotherapy. In particular, neutropenic enterocolitis or typhlitis has had a reported mortality of 50% to 100%. The authors reviewed a series of 77 previously untreated patients with acute myelogenous leukemia begun on treatment from March 1976 to June 1984 to better define the characteristics of typhlitis and its optimum management. Twenty-five patients had episodes of typhlitis, characterized by fever, abdominal pain, and tenderness, occurring during periods of neutropenia. Ten of these patients had watery diarrhea as a major additional symptom, and nine patients had a significant episode of gastrointestinal bleeding. In seven instances, blood culture results were positive, all for intestinal flora. The episodes of typhlitis occurred most frequently during the induction therapy (19 patients). Five patients experienced typhlitis during maintenance therapy, and one patient had acute appendicitis. Two patients had typhlitis during their reinduction therapy, and of note, one had had abdominal symptoms during her initial induction. All patients were treated initially with broad-spectrum antibiotics and bowel rest. Four criteria have been used for surgical intervention: (1) persistent gastrointestinal bleeding after resolution of neutropenia and thrombocytopenia and correction of clotting abnormalities; (2) evidence of free intraperitoneal perforation; (3) clinical deterioration requiring support with vasopressors, or large volumes of fluid, suggesting uncontrolled sepsis; and (4) development of symptoms of an intra-abdominal process, in the absence of neutropenia, which would normally require surgery. Using these criteria, five patients required surgical intervention for typhlitis or its sequelae and one for acute appendicitis. There was one perioperative death resulting from miliary tuberculosis. Among the 21 patients managed medically, there was 1 death resulting from typhlitis in a patient in whom surgery was deferred because of her multiple failures to enter remission.