Understanding the appearance of vestibular symptoms during periods of convalescence after surgery for the treatment of Meniere's disease is important for determining when a patient can return to work as well as the long-term results of the operation. We have treated 20 cases of intractable Meniere's disease with endolymphatic sac drainage & steroid-instillation surgery (EDSS) [Kitahara T, et al., Ann Otol Rhlnol Laryngol in press, 2000] and observed the subjective symptoms and objective vestibular findings using electronystagmogram (ENG) during the subsequent period of convalescence. The average postoperative durations of subjective static and evoked vestibular symptoms were 1.7 and 6.7 days, respectively. Those of spontaneous, positional and positioning nystagmus observed using ENG were 1.2, 2.0 and 7.9 days, respectively. In cases with a long history of Meniere's disease, postoperative static vestibular sensation and positional nystagmus lasted significantly longer than in cases with short histories. In cases with poorly developed temporal bony pneumatization in the area behind the posterior semicircular canal, postoperative evoked vestibular sensations and positioning nystagmus lasted significantly longer than in cases with well developed temporal bony pneumatization. Vestibular symptoms resulting from direct invasion during EDSS were considered to be slighter than those resulting from vestibular neurectomy or gentamicin treatment and almost the same as those resulting from endolymphatic sac surgery.