A 65-year-old woman presented with mycosis fungoides and an anterior mediastinal tumor. Stage Ⅱa mycosis fungoides was treated with bath psoralen plus ultraviolet A, topical corticosteroids, and oral bexarotene. One month later, a surgical resection was performed for the anterior mediastinal tumor, which was a stage Ⅱ thymoma with membrane invasion. Furthermore, adjuvant radiotherapy was performed for anterior mediastinum. The mycosis fungoides lesion exacerbated after 3 months;thus, chemotherapies were performed. The patient died of respiratory insufficiency due to multiple pulmonary metastases of mycosis fungoides 1 year after the operation.