Eight patients with recurrent esthesioneuroblastoma or sinonasal undifferentiated carcinoma of the nasal or sinus cavities were treated with high-dose chemotherapy and autologous bone marrow transplantation. All patients had stage C disease initially and had received extensive prior conventional treatment with surgery, radiotherapy, and chemotherapy. Two patients achieved prolonged relapse-free survival for 18 + and 60 months. The latter patient relapsed at 60 months, but died of progressive disease after a second transplant. Two additional patients remain alive without disease progression at 17 + and 31 + months posttransplant. No deaths occurred secondary to toxicity. Progression of tumor accounted for failure in five patients. High-dose chemotherapy and autologous bone marrow transplantation should be considered as a salvage regimen for selected patients who fail conventional therapy for these diseases.