A patient, a 46-year-old female, with a malignant thymoma spreading to the extrathoracic region is described. She underwent a thoracotomy and received radiation therapy, but the myasthenic symptoms did not disappear. A metastatic thymoma of the right mandibula was removed 9 months after thoracotomy. Further examination revealed metastatic thymomas of the bone and liver. After the operation the patient received combination chemotherapy (vincristine, cyclophosphamide, 6-mercaptopurine, prednisone) and remained asymptomatic for 31 months. She was found to have a metastatic thymoma in the occipital lobe of the brain 3.5 years after thoracotomy, and died from infection of the lung. Distant metastases and chemotherapy in malignant thymoma are reviewed.