A 42-year-old man was admitted with chest pain. A large mass in the anterior mediastinum was seen on a chest X-ray film and confirmed by CT. Surgery was performed, but the tumor was nonresectable because it had invaded the aorta and pulmonary artery, and had disseminated to the pericardium. Invasive thymoma (stage IVa) was diagnosed He initially received two courses of ADOC (50 mg/m2 of cisplatin, 40 mg/m2 of doxorubicin, 0.6 mg/m2 of vincristine, and 700 mg/m2 of cyclophosphamide) at 3-week intervals. Four weeks after the 2 causes of ADOC, he was given 300 mg/m2 of etoposide for five days followed by G-CSF subcutaneously for peripheral blood stem cell collection. After the two courses of ADOC, he received high-dose ICE (1.5 g/m2 of ifosfamide for four days, 400 mg/m2 of carboplatin for three days, and 200 mg/m2 of etoposide for five days) followed by peripheral blood stem cell transplantation (PBSCT). He was given G-CSF after PBSCT, with subsequent rapid neutrophil and platelet recovery. The tumor diminished remarkably in size and complete remission was confirmed pathologically at subsequent thoractomy. Postoperatively, 50 Gy of irradiation was given. These observations suggest that high-dose ICE followed by PBSCT in combination with an ADOC regimen, surgery, and radiotherapy is highly effective and well tolerated in patients with advanced nonresectable thymoma.