Esthesioneuroblastoma (ENB) differs from adrenal neuroblastomas in its histopathologic and biologic characteristics. Hyams grading and Kadish staging have shown correlation with survival. Scant data are available on proliferation indices and prognosis. We retrospectively reviewed the clinicopathologic characteristics of ENB. Both Kadish and UCLA staging systems were used. Hyams grading was simplified into low and high grade. DNA topoisomerase II alpha labeling index (T2alpha LI) was obtained in 8 cases using immunohistochemistry. Of the 19 cases studied, 14 were males and 5 females. Age range was 2 to 62 years (average 27 years). The mass primarily involved the nose in 12 (63%) and paranasal sinuses in 7 cases (37%). Patients presented with nose block in 19 (100%), epistaxis in 10 (53%), proptosis in 9 (47%) and loss of vision in 6 cases (32%). Bony involvement was seen in 7 cases (37%), and intracranial spread in one case (5%). Thirteen (68%) were low-grade tumors and 6 were (32%) high-grade. There was no statistically significant difference between the low- and high-grade ENB in age (years) (p=0.2882), duration of symptoms (months) (p=0.5636), and either in the Kadish (p=0.5456) or the UCLA staging system (p=0.7771). The difference in DNA topoisomerase alpha labeling index between the low- and highgrade ENB (medians: 10.4 and 22.3, respectively) was not statistically significant (p=0.0714), but it was suggestive of a positive association. The results of this study should be interpreted with caution, because of the limited sample size. Three cases recurred locally, one each stage A, B and C, but all low-grade. This preliminary study suggests the need to combine a simplified histologic grading with accurate staging in a reasonable attempt to assess local progression in esthesioneuroblastoma. Larger studies may clarify the role of T2alpha LI in improving histologic grading.