Abscess of the nasal septum caused by trauma is not uncommon. The purpose of this paper is to call attention to the rarer abscess of the septum caused by suppurative inflammation extending from the lateral cellular mass of the ethmoid bone. The pathway of extension may be explained on an anatomic basis. Skillern1 has aptly stated that "the right and left capsules hang down on each side of the nasal septum similar to bags, the lower corner projecting downward like a slender process." To supplement this it may be stated that the outer part of the top of each bag is open. In the articulated skull this open part is closed in by the frontal bone and the lesser wing of the sphenoid bone. The ethmoid bone is one bone, consisting of a vertical plate and two lateral cellular masses. Thus the frontal and sphenoid bones form part of the