Primary small cell carcinoma of the vagina is extremely rare; no standard treatment has been established despite it being highly aggressive. Here, the authors report on a 43-year-old patient who had a mass on the clitoris and no uterine or bilateral adnexal involvement. Vaginal wall biopsy revealed malignant small cell carcinoma. The carcinoma was composed of epithelial cells with round, hyperchromatic nuclei containing few distinct nucleoli, and scanty cytoplasm. Chest computerized axial tomography and pathological bronchoscopy revealed bilateral pulmonary metastases. She received radiotherapy combined with six cycles of chemotherapy (paclitaxel plus cisplatin), and achieved complete response, with complete suppression of the mass and lung metastases. There was no sign of tumor recurrence or distant metastases after 21 months of follow-up.