Osteoma is the most common neoplasm of the paranasal sinuses usually involving the frontal sinus. Osteomas are benign, but can cause serious intracranial or orbital complications. The authors report a frontal sinus osteoma with orbital emphysema in a 16-year-old boy with a history of right-eye swelling after nose blowing. CT showed a right frontal sinus bony mass. Intraoperatively, strands of mucosa extending from the frontal sinus around the periphery of the mass in the right orbit were seen. The mass was excised and the orbital roof repaired. Histopathology was consistent with osteoma. The osteoma facilitated entrance of sinus air in the orbit, resulting in recurrent orbital emphysema with nose blowing. There was no recurrence of orbital emphysema after resection.