An osteoma may originate from cartilage or embryonal periosteum. It may occur externally or within the paranasal sinuses. In most cases, a paranasal osteoma is a solitary lesion and is located in a single sinus. A double osteoma with maxillary sinusitis is rare. A 54-year-old woman was referred for evaluation and treatment of a right maxillary sinus bony lesion. She complained of headache and foul smell after sneezing since 1 month ago. Panoramic radiography revealed two radiopaque masses in the right maxillary sinus. Cone beam computerized tomography images revealed radiopacities with partially corticated borders attached to the medial wall of the right maxillary sinus, near-complete radiopacification of the right maxillary sinus, and peripheral bony thickening due to chronic sinusitis. On histopathologic examination, the removed radiopaque masses were diagnosed as osteomas.