Objective : The purpose of this study is to measure the dimensions of foramen ovale and to localize the zygomatic point using computed tomography[CT] in Korean adults with idiopathic trigeminal neuralgia. Methods : Facial axial CT scans using the orbitomeatal plane were performed in 67patients [39males and 28females; mean age 58.8years] with idiopathic classic trigeminal neuralgia. We measured the size of the foramen ovale and localized the zygomatic point which was a skin marker over the ipsilateral zygoma that approximates the lateral projection of a straight line joining the centers of the two foramen ovale. Results : The axial dimensions of the foramen ovale on the orbitomeatal plane were of average length : $8.18{pm}0.82mm$ [range $6.9{sim}11.5mm$]. width : $4.06{pm}0.86mm$ [$2.5{sim}5.7mm$]. The average distance between the external acoustic meatus and the zygomatic point was $21.64{pm}1.99mm$ [$16.3{sim}25.0mm$] and the average distance of anterior margin of condylar process of mandible to zygomatic point was $4.29{pm}1.19mm$ [$1.0{sim}7.0mm$]. Conclusion : The anatomical understandings including the size of the foramen ovale and localization of the zygomatic point could be helpful in determining a plan of percutaneous approaches to foramen ovale.