A 41-year-old man admitted complaining of dyspnea was found to have lung adenocarcinoma (T4N3M1, stage IV) originating from S1+2. He underwent chemotherapy with carboplatin (CBDCA) and paclitaxel (PTX) and partial remission was obtained. However, on the 11th day of the fourth course of chemotherapy, he developed lower abdominal pain, grade 3 bloody diarrhea and grade 2 vomiting. The stool contained Clostridium difficile (CD) toxin and stool culture revealed C. difficile growth. We diagnosed CD colitis. Fortunately his symptoms recovered by fasting and fluid replacement until the next day. It has been reported that CD colitis occurrs in approximately 2% of patients with gynecological cancers receiving PTX-including chemotherapy. We thus speculate that the CD colitis of the present case was due to PTX. Although the mechanism of CD colitis by chemotherapeutical agents remains undetermined, direct damage to intestinal mucosa or changes in intestinal bacterial flora are possible. As severe CD colitis can be life threatening, we have to be aware of the possibility of it occurring in patients undergoing chemotherapy.