We studied two patients with primary vaginal small cell carcinomas. Their tumors show histologic and ultrastructural neuroepithelial elements similar to those reported in the literature in the cervix and the lung. The clinical behavior of the tumors was aggressive in both patients. Ultrastructural study of small cell genital tract neoplasms is indicated to help classify this disease. Adjunctive therapy may be required for neoplasms of neuroepithelial origin.