The clinical and pathological features of three patients with stage IV thymoma were presented. These patients were classified into stage IV at the first admission according to pericardial dissemination, mediastinal lymph node metastasis, and lung metastasis, respectively. One patient was accompanied with myasthenia gravis. All three patients underwent operations for primary thymoma. The metastatic lesions were also resected as completely as possible. Although postoperative radiotherapy was employed with all patients at the first therapy, chemotherapy was administered to 2 cases. After the first therapy, two patients had pleural dissemination and bilateral multiple lung metastases. They underwent second operations for pleural dissemination and metastatic lung tumors, and postoperative chemotherapy was performed. All three patients are alive (ranged, 2 years 6 months to 4 years 4 months postoperatively). Although follow-up of these three patients is short-term, it seems likely that radiotherapy and chemotherapy following surgery are effective treatments for patients with stage IV thymoma.