Ten patients with Stage II (four) and Stage IV (six) breast cancer were enrolled in a trial of conventional-dose induction therapy followed by high-dose therapy with autologous bone marrow support. Cyclophosphamide, methotrexate, and 5-fluorouracil were given to best response or five courses (Stage II). Those patients without progression were eligible for the high-dose portion of the protocol, which consisted of carboplatin 1,500 mg/m2 and mitoxantrone at either 40 mg/m2 (first five patients) or 50 mg/m2. Two patients did not receive the high-dose portion of the treatment due to progression on induction therapy (one) and insurance refusal (one). Of the remaining eight patients who completed the high-dose portion of the protocol, three were Stage II, of whom one died of transplant-related complications, one progressed, and one is alive and free of disease 24 months after therapy. Of the five Stage IV patients, two achieved a partial remission, one of whom died of progressive disease 1 year after therapy and the other died of BMT-related complications; of the other three Stage IV patients, one had stable disease and died at +9 months, one with progression died at +3 months, and one died of BMT-related causes. Overall, three patients died of infectious complications, with two having alpha streptococcal septic shock syndrome.