We report a rare case of recurrent thymoma with pleural dissemination invading the intervertebral foramen. A woman with Masaoka's stage IVa thymoma with myasthenia gravis (MG) underwent macroscopically complete resection. After 45 months, she developed back pain. Computed tomography (CT) of the chest demonstrated a mass in the right thoracic cavity invading the intervertebral foramen between thoracic vertebrae 10 and 11. She underwent complete resection of the tumor and postoperative radiotherapy. The resected specimen was histologically diagnosed as a pleural dissemination from thymoma. There has been no local recurrence.