PURPOSE We studied high-dose cyclophosphamide, cisplatin, and carmustine (CPA/cDDP/BCNU) with autologous bone marrow support (ABMS) as consolidation after standard-dose adjuvant chemotherapy treatment of primary breast cancer involving 10 or more axillary lymph nodes. PATIENTS AND METHODS One hundred two women with stage IIA, IIB, IIIA, or IIIB breast cancer involving 10 or more lymph nodes at surgery were registered; 85 were eligible, treated, and assessable. Patients were treated with four cycles of standard-dose cyclophosphamide, doxorubicin, and fluorouracil (CAF), followed by high-dose CPA/cDDP/BCNU with ABMS. RESULTS Actuarial event-free survival for the study patients at a median follow-up of 2.5 years is 72% (95% confidence interval, 56% to 82%). Comparison to three historical or concurrent Cancer and Leukemia Group B (CALGB) adjuvant chemotherapy trials selected for similar patients showed event-free survival at 2.5 years to be between 38% and 52%. Therapy-related mortality was 12%; pulmonary toxicity of variable severity occurred in 31% of patients. Quality-of-life evaluations indicate that patients are functioning well without major impairments. CONCLUSION High-dose consolidation with CPA/cDDP/BCNU and ABMS after standard-dose CAF results in a decreased frequency of relapse in patients with high-risk primary breast cancer compared with historical series at the median follow-up of 2.5 years. Evaluation in a prospective, randomized trial is warranted and currently underway.