A phase II study of doxorubicin (Adriamycin)-based induction chemotherapy followed by cyclophosphamide/BCNU (CyBCNU) intensification and autologous bone marrow transplantation (ABMT) was conducted in 20 consecutive women with hormone-resistant metastatic breast cancer referred to our center. Of these 20 women, aged 24 to 56 (median age, 41), 9 had complete remission and 11 had partial remission after induction chemotherapy. Predominant sites of metastases included liver (5), lung (4), bone/bone marrow (5), and soft tissue (6). The dose of cyclophosphamide was 160 mg/kg and the dose of BCNU, 600 mg/m2, followed by infusion of a mean 2.30 x 10(8) nucleated marrow cells per kilogram of body weight. All patients achieved durable engraftment. Three patients remain disease-free at 62+, 67+, and 73+ months; two of these were in complete remission before ABMT. Actual relapse-free survival at 5 years is 15% and median survival from ABMT is 17 months. Induction chemotherapy followed by CyBCNU intensification in metastatic breast cancer can achieve prolonged relapse-free survival in 15% of patients, some of whom may be cured.