Conclusions: The comparison of noninvasive standard evaluation of endolymphatic hydrops in Meniere's disease and the endolymphatic space in healthy volunteers using magnetic resonance imaging (MRI) evaluation should be carried out first. Objective: To compare the standard evaluation of endolymphatic hydrops in Meniere's disease and the endolymphatic space in healthy volunteers in the cochlea and the vestibule in the same age group by applying noninvasive intratympanic gadolinium (Gd) perfusion through the eustachian tube and three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging (3D-FLAIR MRI). Methods: This was a prospective study. 3D-FLAIR MRI was performed with a 3 Tesla (3 T) unit 24 h after intratympanic administration of Gd through the eustachian tube in 6 patients with medically active and intractable Meniere's disease and 20 healthy volunteers. Pure tone test and tympanometry were performed 24 h before Gd was administered, and 24 h and 1 month after Gd administration. Results: Gd was present in the perilymph of the inner ear, which clearly displayed the endolymphatic space on 3D-FLAIR MRI with a visible borderline between the perilymph and the endolymph. In 45-55-year-old healthy volunteers, the normal value for the endolymphatic space in the cochlea ranged between 8% and 26%, and that in the vestibule was between 20% and 41%. According to the normal value for the endolymphatic space, four of six patients had a ratio of more than 26% in the cochlea; moreover, four of six patients had a ratio of more than 41% in the vestibule. All the patients had a ratio of more than the normal value in the cochlea and/or the vestibule. No significant changes in pure tone test and tympanometry were noted.