A 71-year-old man was admitted to our hospital with vertigo and general fatigue. Examination of his blood and bone marrow showed pure red cell aplasia. His chest X-ray film revealed an anterior mediastinal mass and a nodular shadow in the right lower lobe. Extended thymothymectomy and right lower lobectomy were done. The mediastinal mass appeared to be an invasive thymoma and the nodular shadow in the right lower lobe proved to be from an adenocarcinoma. The patient was treated with radiation and steroids. Thymoma, pure red cell aplasia, and lung cancer had not recurred and he was alive and well as of 2 years after surgery.