The first patient, a 68-year-old woman, presented neutropenic fever and hemorrhagic diarrhea on the sixth day of a combination chemotherapy of carboplatin and paclitaxel. The second patient, a 30-year-old man, presented neutropenia and diarrhea on the tenth day of the second cycle of a combination chemotherapy of cisplatin and vinorelbine. In both patients, abdominal computed tomography scan showed thickening of the colon wall and pericolic edema, and the ultrasonography revealed echogenic thickening of the colon walls. These findings confirmed the diagnosis of neutropenic enterocolitis. After the treatments, we changed the anticancer drug regimen; and successfully achieved partial responses.