OBJECTIVES:We sought to clarify possible pathological conditions of the bony portion of the eustachian tube (ET) in patients with ET stenosis. METHODS:We measured the total length, the cross-sectional area of the bony frame, and the air space of the ET lumen at an interval of 1 mm on the reconstructed computed tomographic images of the ET using a multiplanar reconstruction method on 20 normal subjects (control group) and 25 patients with stenotic ET judged by the inflation test (stenotic group). RESULTS:In the cross-sectional areas, both the bony frame and air space were significantly smaller in the stenotic group than in the control group. The soft tissue ratio was significantly greater in most parts of the mid-bony portion and the tympanic orifice of the stenotic group than in those of the control group. At the anterior tip of the bony portion, only the bony frame was found to be significantly smaller in the stenotic group than in the control group. CONCLUSIONS:We suggest that a smaller framework of the bony ET may possibly be related to the pathogenesis of ET stenosis.