Cholesteatoma of the maxillary sinus is rare. There are approximately 44 cases reported in the world literature. The most frequent symptoms and signs at presentation are nasal obstruction, rhinorrhea, headache, facial swelling and tenderness. It's difficult to be diagnosed just with a clinical presentation and radiologic findings. A 36-year old man visited our hospital with the symptom of left nasal obstruction for 3 months. Anterior rhinoscopy showed a pale polypoid-like mass over left nasal cavity. A CT scan of the paranasal sinuses showed a large, homogeneous, expansile mass over left maxillary anturum. Endoscopic sinus surgery was performed to remove the maxillary sinus mass. The pathology showed a maxillary sinus cholesteatoma. Recurrence has not occurred during the 6-month follow-up. In the reported cases, most surgeons suggested Caldwell-Luc operation with complete cholesteatoma excision. Although our patient still requires long term follow-up in view of the risk of recurrence and malignant transformation, we recommend that endoscopic sinus surgery is a good option for cholesteatoma of the maxillary sinus.