The purpose of this study was to determine the outcome of high-dose therapy with autologous hematopoietic stem cell support (autotransplants) in men with breast cancer. We studied 13 men receiving autotransplants for breast cancer and reported to the Autologous Blood and Marrow Transplant Registry (ABMTR) by 10 centers. Six men had stage 2 breast cancer, four had stage 3, and three had metastatic breast cancer. Of twelve tumors tested, all were estrogen receptor positive. Median age at transplant was 50 years. The most common conditioning regimen was cyclophosphamide, thiotepa and carboplatin (n = 5); the remaining eight men received other alkylator-based regimens. Three men received bone marrow, eight received blood stem cells, and two received both for hematopoietic support. All patients had hematopoietic recovery. There were no unexpected regimen-related toxicities. Of 10 men receiving autotransplants as adjuvant therapy, three relapsed 3, 5 and 50 months post-transplant and died 16, 19 and 67 months post-transplant. Seven of 10 are disease-free with median follow-up of 23 months (range 6-50 months). Of three men treated for metastatic breast cancer, one had progressive disease and two recurrent disease at 6, 7 and 16 months post-transplant. In conclusion, results of autotransplants for male breast cancer appear similar to those reported for women receiving autotransplants for breast cancer.