The response of human breast cancer to drugs and radiation is dose-dependent, with higher doses producing increased response rates. However, dose escalation of several agents active against breast cancer is limited by bone marrow toxicity. This limitation can be overcome in some instances by transplantation of bone marrow cells. We evaluated 27 trials of bone marrow autotransplants in 172 patients who received single or multiple drug chemotherapy, radiation, or both. The overall response rate was 58%. Response rates were highest in trials involving multiple alkylating agents (76%) or previously untreated patients (81%). These data suggest that high-dose therapy and bone marrow autotransplants can produce remissions in patients with advanced breast cancer unresponsive to conventional therapy. A critical evaluation of this approach will require controlled trials in high-risk persons.