Cases of foreign body in the paranasal sinus sometimes have been reported. Most common site is the maxillary sinus. But ethmoid sinus, sphenoid sinus, and frontal sinus are rare. The authors experienced a large metal foreign body in the ethmoid sinus in 26 year-old male. The foreign body was removed under C-arm fluoroscopy through the right external ethmoidectomy procedure. Post-operative diplopia and visual defect were not developed.