One hundred women with metastatic breast cancer (MBC) underwent high-dose chemotherapy with autologous stem cell rescue at our institution beginning in 1986. The patients underwent induction chemotherapy from June 1986 to December 1993. Patients who showed stable or responsive disease underwent HDC with cyclophosphamide (CY) at 7.5 g/m2 and thiotepa (TPA) at 675 mg/m2 or the same doses of CY and TPA with carmustine at 450 mg/m2. The source of stem cell rescue was either BM alone, BM and G-CSF-mobilized peripheral blood progenitor cells (PBPC) or PBPC alone if patients had BM involvement with MBC. With a median follow-up of 62 months (range 1-109 months), median survival from reinfusion was 16 months with a 5-year survival of 19+/-4%. The median event-free survival (EFS) was 8 months with a 5-year EFS of 11+/-3%. Patients achieving a complete response to induction therapy showed a higher 5-year EFS from reinfusion of 31+/-8% in contrast to 3+/-3% (P = 0.006) for patients who achieved a partial response to induction therapy prior to HDC. Marrow involvement or source of stem cell rescue did not affect outcome. Our mature results confirm that high-dose chemotherapy with autologous stem cell rescue can confer a prolonged DFS in a subset of women with MBC. However, the high rate of relapse remains a universally disturbing problem in this patient population.