We describe our experience of treatment for a giant esophageal malignant fistula, which has not been reported previously. A 36-year-old woman who was diagnosed as having massive esophageal small cell carcinoma with metastases was treated with chemoradiotherapy. However, a giant esophagomediastinal fistula appeared due to shrinkage of the massive tumor, and all anti-cancer treatment was suspended. However, chemoradiotherapy was restarted at the request of the patient despite the presence of the fistula. After restarting treatment, the giant esophageal fistula was naturally closed despite intensive chemoradiotherapy, and the patient became able to eat and drink. Although the patient finally died, her QOL and prognosis seemed to be improved by the chemoradiotherapy. Anti-cancer treatment could be safely performed despite the presence of a giant fistula. The giant fistula closed while intensive chemotherapy was administered to the patient. Therefore, the presence of a fistula may not be a contraindication for curative chemoradiotherapy. Completion of treatment with proper management and maintenance of patients would be of benefit to patients with fistula. We describe our experience of treatment for a giant esophageal malignant fistula, which has not been reported previously. A 36-year-old woman who was diagnosed as having massive esophageal small cell carcinoma with metastases was treated with chemoradiotherapy. However, a giant esophagomediastinal fistula However, due to shrinkage of the massive tumor, and all anti-cancer treatment was suspended. However, chemoradiotherapy was restarted at the request of the patient despite the presence of the fistula. After restarting treatment, the giant esophageal fistula was naturally set over intensive chemoradiotherapy , and the patient became able to eat and drink. the therapist finally died, her QOL and prognosis seemed to be improved by the chemoradiotherapy. Anti-cancer treatment could be safely performed despite the presence of a giant fistula. The giant fistula closed while intensive chemotherapy was administered to the patient. therefore, the presence of a fistula may not be a contraindication for curative chemoradiotherapy. Completion of treatment with proper management and maintenance of patients would be of benefit to patients with fistula.