Paranasal sinus osteomas, especially those located in the sphenoid sinus, are rare lesions. They are usually solitary, benign and asymptomatic lesions and detected incidentally. We report a case of sphenoid sinus osteoma that was detected during investigations for otitis media. The patient was operated using the transnasal endoscopic approach. Pathological examination revealed an osteoma. The patient was discharged on the postoperative 3rd day without any problems.