A 66-year-old man was found to have both advanced cancer of the middle thoracic esophagus and advanced cancer of the middle third of the stomach with paraaortic lymph node metastases. The prognosis was poor because of local advanced disease and distant metastasis. The patient was therefore given combined chemotherapy with TS-1 and cisplatin. TS-1 (80 mg/day) was administered on days 1 to 5, 8 to 12, 15 to 19, and 22 to 26 (weekday-on/weekend-off schedule), and cisplatin (70 mg/m2 intravenously over the course of 2 hours) was administered on days 1 and 15 of a 28-day cycle. After 2 courses of chemotherapy the esophageal lesion had a complete response, and the gastric lesion had a partial response (reduction ratio, 71.4%). However, stomatitis and anorexia of grade 2 (NCI-CTC) occurred. Two courses of TS-1 alone (80 mg/m2) were therefore given. The esophageal lesion continued to show a complete response and the gastric lesion a partial response (reduction ratio, 85.7%). There was no change in the para-aortic lymph node metastasis (No. 16a2 latero). No adverse reaction to chemotherapy was severer than grade 3, and a good response was obtained. These findings indicate that chemotherapy with a combination of TS-1 and cisplatin is effective against advanced esophageal cancer and advanced gastric cancer.