목적: There has been many therapeutic trials in eustachian tube(ET) dysfunction.It is important to figure out the location between internal carotid artery (ICA) and ET for ET surgery. Although many papers have been reported about anatomical relation of ET, ICA, middle ear and nasopharynx, it is true that there's few studies which are focus on between ET and ICA. This study is aimed to measure the distance and correlation between ET and ICA by using Computed Tomography (CT) and to provide significant information about ET surgery. 방법:January 2005 to May 2011 Paranasal Sinus CT(Contrast enhance) of 200 patients (400 ears) were enrolled in this study. The patients were consisted of 100 males and 100 females who were older than 15, and they are divided by 7groups each 10years.The central axis was set up at the slice which expressed ET,ICA, Rosenmuller fossa(RF) most clearly. The shortest distance between ICA and anterior cushion of ET,ICA and posterior cushion of ET,RF and ET ere measured. The angle between the line of ET plane to nasal septum and that of nasal septum to ICA, and distance from ICA to ET line were also measured 결과:The shortest distance from ICA to the anterior cushion of ET, the posterior cushion of ET, RF were longer in male. The shortest values were 16.65mm, 10.76mm, 1.61mm. Also the shortest distance from ICA to ET line was longer in male(4.85mm). The minimum distance from ET to ICA was 1.68 mm. However the angle was smaller in male. According to age distribution,distance from ICA to each custion of ET were shortest at 35-44 year-old group.ICA~RF was shortest at over 75 year-old group.Angle was smallest at 15-24 year-old group, largest at 65-74 year-old group. Distance from ET to ICA was shortest at 55-64 year-old group. 결론:Distance and correlation between ET and ICA represents a variety of distribution according to sex and age. During a surgery related to ET, an operator should be aware of correlation between ET and ICA through preoperative radiologic evaluation.