The prognosis of patients with de novo stage IV breast cancer seems to be similar to that of patients with metastatic disease. Because these patients have not been exposed to prior therapy, the use of high dose chemotherapy (HDCT) may be beneficial. Twenty-four newly diagnosed (median age 42) responding metastatic breast cancer patients underwent HDCT (Stamp V) and stem cell support as their initial treatment. The predominant sites of metastatic disease were bone (12), lung (5), liver (2), lymph nodes (6), marrow (4), and soft-tissue (1). Estrogen/progesterone receptors were positive in 35%, negative in 45%, and unknown in 20%. Before transplantation, 10 patients were in complete remission (CR), 6 were in partial remission (PR), and 8 were inevaluable. Radiotherapy was administered to sites of documented metastatic disease. Tamoxifen was given to patients with receptor positive and unknown tumor status. After a median follow-up of 60 months from diagnosis (range 42 to 96 months), 15 patients have relapsed and 10 died. Mean and median progression free survival from transplant are 53 (SE 6.6, CI 40-66) and 60 (SE 18, CI 25-96) months, respectively. The median survival has not yet been achieved (>6 years). There was no treatment-related mortality. The use of HDCT in patients with chemosensitive, de novo metastatic breast cancer is safe and well tolerated. Overall clinical outcome is good; however, this study cannot determine whether this was due to treatment or selection bias.