We identified 24 children treated for malignancies between 1962 and 1992 who had antemortem diagnoses of typhlitis that were confirmed on review. The study criteria specified the presence of fever, abdominal pain, and tenderness, with radiological evidence of right-sided colonic inflammation. Typhlitis was most frequent in patients treated for acute leukemias. Computed tomography and ultrasonography were more sensitive than plain radiography (false-negative rates, 15%, 23%, and 48%, respectively). The wider availability of these sensitive procedures and the increased intensity of chemotherapeutic regimens may account for a marked increase in the incidence of typhlitis over the past 5 years. Most patients responded to aggressive medical management, and typhlitis was fatal in only two cases (1 of 21 cases managed medically and 1 of 3 taken to surgery). Seven patients are alive > 1 year following the diagnosis. These findings contrast with prior descriptions of typhlitis as a preterminal event. Computed tomography and/or ultrasonography should be performed in all neutropenic patients with right-lower-quadrant signs to permit prompt diagnosis and treatment.