Ménière's disease (MD) is characterized by episodic vertigo, fluctuating hearing loss and tinnitus. Vestibular migraine (VM) is a relatively new disorder that is characterized by episodic vertigo or dizziness, coexisting migraine and absence of hearing loss. It is occasionally difficult to distinguish between VM and vestibular MD with headache. Because endolymphatic hydrops (EH) is a characteristic sign of MD, we attempted to evaluate endolymphatic space size in both diseases. Endolymphatic space size in the vestibule and the cochlea was evaluated in seven patients with VM and in seven age- and sex-matched patients with vestibular MD. For visualization of the endolymphatic space, 3T magnetic resonance imaging was taken 4 h after intravenous injection of gadolinium contrast agents using three-dimensional fluid-attenuated inversion recovery and HYbriD of reversed image of positive endolymph signal and native image of positive perilymph signal techniques. In the vestibule of VM patients, EH was not observed, with the exception of two patients with unilateral or bilateral EH. In contrast, in the vestibule of patients with vestibular MD, all patients had significant EH, bilaterally or unilaterally. These results indicate that endolymphatic space size is significantly different between patients with VM and vestibular MD.