Background: Curative treatment of malignant thymoma is resection; however, this may be precluded by invasion of vital organs. Patients and methods: Two patients with extensive intrathoracic spread of thymoma (Stages III and IV A) are presented. Treatment involved a combination of resection, radiotherapy and chemotherapy. Results: One patient survived 9 years, 4 months, but eventually died of metastatic spread; the other one is well and without evidence of disease 30 months after treatment. Conclusions: Thymoma is a slow-growing tumor. Successful surgical treatment in advanced cases is possible, if aided by radiotherapy and chemotherapy. The adjuvant therapy converts a non-resectable tumor to a resectable one.