Fourteen patients with refractory metastatic breast cancer were treated with high dose chemotherapy and autologous hematopoietic stem cell rescue. All patients received cyclophosphamide (7.5 g/m2 over 3 days) and thiotepa (150-225 mg/m2 over 3 days), three patients in addition received melphalan (4.5 mg/kg), and seven patients received carmustine (150-562 mg/m2). Toxicities included pancytopenia, infection, hemorrhagic cystitis, skin rash, nausea, vomiting, diarrhea, and mucositis. There was one toxic death secondary to sepsis and ventricular tachycardia. The overall response rate was 77% including a 15% complete response rate. The overall median survival for all patients was 6.0 months (range 2-22 months). The median survival for nonresponders was 3.5 months. The median duration of response was 89 days (range 40-262). In our experience high dose chemotherapy with autologous stem cell reinfusion produces a high response rate in refractory breast cancer. However, because of the short duration of response and overall survival, we feel this type of therapy should be utilized earlier in the course of disease.