The early diagnosis of acoustic neuroma is important for radical removal of it with lesser morbidities. Among the various methods of diagnosis the roentgenologic study, especially the internal auditory cisternography, was considered to be the most reliable method and, for roentgenologic study, it is required to know the normal dimension of the internal auditory meatus. There are two methods for internal auditory meatal measurement ; one is indirect such as the conventional roentgenography, laminography and cisternography and the other is direct measuring method using rubber case of Amjad, A.H. et al. Authors measured the anatomical dimensions of internal auditory meatus of normal Korean adult with regular rubber base impression material.