The purpose of this study was to investigate the initial clinical features and subsequent outcomes in patients with adult leukemia with typhlitis or neutropenic enterocolitis. A retrospective review of 10 episodes of neutropenic enterocolitis in nine patients (age range, 21–71 years) with acute leukemia from March 1, 1990, through February 28, 2002, was conducted. In clinical presentations, fever appears in all patients, followed by abdominal pain or tenderness (90%) and diarrhea (60%), respectively. In particular, three cases were coincidentally diagnosed as leukemia before any chemotherapy. The most common diagnostic modality used for the diagnosis of neutropenic enterocolitis was computed tomography (CT) scan (seven episodes). Medical treatments, including broad-spectrum antibiotics, bowel rest, and total parenteral nutrition, were applied to seven patients. Laparotomy with bowel resection was performed on two patients with bowel necrosis and severe peritonitis. Of all nine cases, six were fatal as a result of sepsis, a common complication of neutropenic enterocolitis. As the incidence of neutropenic enterocolitis increases in patients with acute leukemia, EPs should be alert and make an early diagnosis of this rapidly deteriorated and life-threatening disease.