Introduction: The sphenoid adenoid cystic carcinoma is a rare malign neoplasm, in the head and neck and when located in the paranasal sinuses, it is formed in the minor salivary glands. It grows slowly and is characterized by a large invasion of the adjacent tissues, and also has a large capacity of metastasis. The surgery associated with post-operative radiotherapy is used as treatment. Objective: To describe a case of sphenoid sinus adenoid cystic carcinoma in a male, black, 62 year patient. Case Report: N.L.B., 62 years of age, male, had bloody rhinorrhea for 6 months associated with bilateral nasal obstruction. The nasofibroscopy showed lesion of polypoid aspect in the left nasal cavity. He was submitted to biopsy and the anatomopathological exam showed adenoid cystic carcinoma and the patient was forwarded to oncology. Conclusions: The importance of conducting the differential diagnosis between chronic nasosinusal infection and nasosinusal tumors.