Conclusions: Noninvasive standard evaluation of normal endolymphatic space and endolymphatic hydrops using magnetic resonance imaging (MRI) in various age groups is reported for the first time. Objective: To compare the standard evaluation of endolymphatic space in healthy volunteers in the cochlea and the vestibule among different age groups by applying noninvasive intratympanic gadolinium (Gd) perfusion through the eustachian tube and three-dimensional fluid-attenuated inversion recovery MRI (3D-FLAIR MRI). Methods: This was a prospective study. 3D-FLAIR MRI was performed with a 3 T unit 24 h after intratympanic administration of Gd through the eustachian tube in 60 healthy volunteers aged 20-55 years. Pure-tone test and tympanometry were performed 24 h before and 1 week after Gd administration. Results: There was no significant difference in the ratios of the area of the endolymphatic space to that of the fluid space in the cochlea and the vestibule between males and females, or among 20-30-, 31-44-, and 45-55-year-old healthy volunteers. In 20-55-year-old healthy volunteers, the normal value of the endolymphatic space in the cochlea ranged between 7% and 27%, and that in the vestibule was between 17% and 39%. No significant changes in pure-tone test or tympanometry were noted.