Primary choriocarcinoma of sinonasal tract has not been previously documented. The aim of the study was to report, for the first time, 2 cases of primary sinonasal choriocarcinoma. The differential diagnosis is discussed and also the theories concerning the histogenesis of this neoplasm are briefly reviewed. Two male patients of 44 and 49 years of age complained of epistaxis and nasal obstruction of 2-week duration. Computerized axial tomographic scan of the head revealed an opacity of the left nasal cavity in one patient and a destructive lesion of the maxillary sinus in the other. Histopathologically, the lesions disclosed a dual cell population composed of cytotrophoblastic cells with uniform, round nuclei, clear cytoplasm, admixed with large multinucleated syncytiotrophoblastic cells, with bizarre nuclei, and abundant eosinophilic cytoplasm. Immunohistochemically, the tumors were notable for strong keratin and beta-chorionic gonadotrophin (HCG) positivity. The serum levels of HCG were 13 000 and 779 mIU/mL, respectively. One patient treated with maxillectomy, postoperative radiotherapy, and 5 courses of VIP chemotherapy (cisplatinum, etoposide, ifosfomide) died with brain metastases 10 months after diagnosis. The other patient received 4 courses of etoposide, and he is alive without tumor, 10 months after diagnosis. The serum levels of HCG are still negative. The present cases demonstrated the widespread distribution of germ cell tumors in the human body and lead to further support of the existence of primary choriocarcinomas in the sinonasal tract. Correct identification of this neoplasm is therefore important for institution of specific therapy.