Chemotherapeutic agents have been shown experimentally to have a dose-response relationship in drug-sensitive cancer. This suggests that high-dose chemotherapy (HDC) might improve the therapeutic outcome in breast cancer. The emergence of modern supportive measures like peripheral blood stem cell rescue has significantly decreased the toxicity and cost of HDC. HDC is being employed for patients with metastatic and high-risk breast cancer (> 10 involved axillary lymph nodes). Randomized phase III trials are urgently needed. At the moment patient with breast cancer should only be treated with HDC in context with a clinical trial.