Forty-nine patients with esthesioneuroblastoma were treated at the Mayo Clinic between 1951 and 1990. Their clinical manifestations and treatment results were reviewed to identify possible prognostic factors. The 5-year survival rate for all patients was 69%. Tumor progression occurred in 25 patients (51%; no local control in 6 and local recurrence in 19). Metastasis was found in 15 patients (31%; regional in 10 and distant in 9). Nineteen patients died directly from metastatic or intracranial tumor extension. The pathological grade of the tumor was the most significant prognostic factor identified. The 5-year survival rate was 80% for the low-grade tumors and 40% for the high-grade tumors (P = 0.0001). Surgical treatment alone is effective for low-grade tumors if tumor-free margins can be obtained. Radiation is used for low-grade tumors when margins are close, for residual or recurrent disease, and for all high-grade cancers. The poor prognosis associated with high-grade tumors may also mandate the addition of chemotherapy. Recurrent tumor and regional metastasis should be treated aggressively because this approach has been shown to be worthwhile. A craniofacial resection is now the surgical procedure performed in all cases. Because recurrence can occur after 5 or even 10 years, long-term follow-up is mandatory.