Three patients with breast cancer with poor prognosis were treated with high-dose chemotherapy (HD-CT) and peripheral blood stem cell transplantation (PBSCT) as adjuvant treatment. After radical mastectomy, the consolidation chemotherapy with Adriamycin 50 mg/m2, Cyclophosphamide 1,000 mg/m2, Vincristine 1.0 mg/m2 and Methotrexate 200 mg/m2 with Leucovorin rescue was started. Recombinant human granulocyte colony stimulating factor (rhG-CSF) was also added for early recovery from myelosuppression. This combination chemotherapy was given every 3 weeks for 3 courses, and after the 2nd and 3rd courses, peripheral blood stem cells (PBSC) were collected and cryopreserved. HD-CT with Cyclophosphamide 2,000 mg/m2/day, Thio-TEPA 200 mg/m2/day, and Etoposide 300 mg/m2/day, were administered for 3 consecutive days, and after 48 hours of last doses, frozen-thawed PBSC (6.4-8.9 x 10(4)/kg of CFU-GM) were administered. rhG-CSF was also added. HD-CT and PBSCT were well tolerated, recovery from myelosuppression of the HD-CT was very quick and no serious side effects were observed.