Brown tumor is a non-neoplastic bone lesion that develops secondary to hyperparathyroidism and it is very rare in the maxillofacial region. We report the case of a 59-year-old man who presented with pain and a swelling in the left cheek. Computed tomography (CT) demonstrated an expansile and radioluscent lesion in the left maxillary sinus. Incisional biopsy was performed, and the diagnosis was Brown tumor. Brown tumor must be considered in the differential diagnosis of expansile lesions of maxillary sinus.