An osteoma is slowly growing benign tumor of bone, which occasionally produced symptoms of a space-occupying lesion. Osteomas of the ethmoidal sinus may enlarge to involve the majority of the ethmoidal cells or extend into the frontal sinus, orbit or sphenoidal sinus. Growth in the direction of the orbit results in downward or outward displacement of the orbital contents. The external ethmoidectomy approach is the route of choice for removal of osteoma of the ethmoid. Recently the authors had experienced one case of the ethmoidal sinus which was removed by external ethmoidectomy.