Olfactory neuroblastomas are known to be rare and clinically malignant tumors. The authors analyzed the clinical features, long-term treatment outcomes, and prognostic factors related to 21 cases of olfactory neuroblastomas, treated between January 1979 and October 2000, retrospectively reviewed with medical records and radiologic findings. The mean follow-up period was 28.7 months (range 4-178). The extent of tumor was classified according to the UCLA staging system. Statistical analysis for survival was done using the Kaplan-Meier method and the log-rank test. The mean age was 27 years (13-62), the peak incidence occurred in the second decade (8/21, 38%), and the male to female ratio was 13:8. According to the UCLA staging system, there were 3 cases of T1, 5 of T2, 6 of T3, and 7 of T4. The 5-year survival rate was 21.3% and the average survival time was 28.9 months. The group (n = 14) undergoing radical surgical resection as the primary modality, registered a higher survival rate than the radiation and chemotherapy group (n = 7), with 2-year survival rates being 76.2% vs. 14.3%, respectively (p = 0.0274). The early stage (T1, T2) groups exhibited a better survival rate than the advanced (T3, T4) groups with 5-year survival rates being 38.1% vs. 9.1%, respectively (p = 0.0336). The mean recurrence free time was 7.8 months (range 1-25). From these findings we could conclude that tumor detection in the early stage, radical surgical resection as the primary treatment modality, and regular follow-up with radiologic evaluation for recurrence or metastasis, represent important factors for an improved outcome.