Large-cell neuroendocrine carcinoma in the thymus is a rare cancer that is more aggressive and leads to a poorer prognosis than other thymic epithelial tumors. A 67-year-old woman presented with an anterior mediastinal mass in the thymus. Histological examination after thymectomy revealed large-cell neuroendocrine carcinoma in the thymus. Although the patient received postoperative chemotherapy and radiotherapy, a distant relapse was detected 6 months after the surgery. We reviewed nine cases of this rare cancer that have been reported in Japan. There is no evidence of to support postoperative therapy for large-cell neuroendocrine carcinoma in the thymus. However, it is essential to accumulate and study these cases to understand this disease and prolong patient survival.