From 1996 to 2000, high-dose chemotherapy with haematopoietic stem-cell support was used as an adjuvant treatment strategy for management of primary high-risk breast cancer patients with more than five positive nodes, This single institution study included 52 women aged less than or equal to 56 years with primary operable breast cancer and greater than or equal to 6 tumour-positive axillary lymph nodes. The treatment regimen consisted of at least three initial courses of FEC (5-fluorouracil, epirubicin, cyclophosphamide) followed by high-dose chemotherapy (cyclophosphamide, thiotepa, carboplatin) supported by autologous peripheral blood stem-cell reinfusion. This study focuses on quality control including evaluation of toxicity, supportive therapy and assessment of the stem-cell products. Cytokeratin 19 positive cells were found in the stem-cell product from 3/37 patients. Data regarding organ toxicity were used for evaluation of short- and long-term side effects. Substantial acute toxicity and frequent catheter-related infections were found. Long-term toxicities included reduced lung diffusion capacity (n = 36), fatigue (n = 14), arthralgia/myalgia (n = 10), neurotoxicity (n = 9) and memory loss (n = 4). However, most toxicities were grade 1-2 and reversible within two years. No treatment-related death occurred. Within a median follow-up of 30 months (range, 11-57), 25% of the patients had relapsed. Recurrence-free survival was 75% and overall survival was 88% three years after the start of treatment. Overall, high-dose chemotherapy was relatively well tolerated, with manageable toxicity and an acceptable requirement of supportive therapy. Until now, high-dose chemotherapy has not proven superior to conventional-dose adjuvant chemotherapy, therefore it is necessary in the future to focus on well-designed randomized studies.