This study was conducted to evaluate the efficacy of high-dose thiotepa, melphalan and carboplatin (TMCb) regimen in 27 patients undergoing autologous stem cell transplantation (ASCT) for metastatic breast cancer. A total of 27 patients with stage IV breast cancer underwent ASCT following thiotepa (500 mg/m(2)), melphalan (100 mg/m(2)) and carboplatin (12004350 mg/m(2)). Of 27 patients, 17 had refractory relapse, eight had responding relapse, and two had no evidence of disease (NED) at the time of transplant. In all, 11 patients had only bone disease, nine had bone plus visceral disease, three had only visceral disease, and two had locoregional recurrent disease. The median time from diagnosis to transplant was 1081 days (range 180-2341). Staging for evaluation of response was performed 4-6 months after transplantation. Five patients were not evaluable (NE) for response because of NED at transplant (n = 2) or early death due to transplant-related complications (n = 3) (two of viral pneumonia and one of regimen-related toxicity) occurring at a median of 4 days (range 11-46) post-transplant. One of the two patients who was NED at the time of transplant is still NED on day 760 post-transplant. Seven of 15 refractory (47%) and 5/7 (71%) responsive patients with evaluable disease achieved a complete response of all measurable disease or all soft-tissue disease with at least improvement in bone lesions. Of 27 patients (37%),(10) are alive and progression-free, a median of 582 days (range 410-1380) after treatment, 6/17 (35%) with refractory disease and 4/10 (40%) with responsive disease. The probability of progression-free survival (PFS) for all patients was 0.50. The probabilities of PFS at 2 years for patients with refractory (n = 17) and responsive (n = 10) disease were 0.42 and 0.60, respectively. PFS at 2 years for the 14 patients who were NED or achieved CR/PR* following-HDC was 0.67. PITS at 2 years for patients who did not achieve CR/PR* following-DHC was 0.33. These preliminary data suggest that high-dose TMCb followed by autologous stem cell transplantation is an effective regimen for patients with advanced breast cancer and may be comparable to some previously used regimens.