A 74-year-old woman diagnosed with poorly-differentiated neuroendocrine carcinoma originating from the ascending colon was referred to our hospital. She had felt anorexia, abdominal pains and her (ECOG) performance status was 3. Her CT scan showed that some abdominal lymph nodes were swelling and that there were many metastatic lesions occupying most of the liver. We started chemotherapy with cisplatin and irinotecan according to a regimen for small cell lung cancer. Considering her poor PS, both of the drugs were administered at 30mg/m² twice 4 weeks in the first course of chemotherapy. Her anorexia and abdominal pains immediately disappeared, and CT scan showed that all of the metastases were decreased in size. After 4 courses, however, some of the metastatic lesions were increased in size. She died 8 months after diagnosis. The tumor marker doubling time was 17 days.