A case of perilymph gusher was reported.The patient was an 11-year-old boy with bilateral congenital mixedhearing loss. On the suspicion of a fixed stapes footplate, an exploratory left tympanotomy was performed. On making a control hole in the footplate, an abrupt gush of perilymph was observed. Sealing of the hole was effectively done immediately with temporal fascia and muscle. Postoperative examination revealed that the left hearing acuity wasremained at the preoperative level. The computed tomography scan of the temporal bone demonstrated normal contours of the inner ear with abnormal bony defects of the fUndi of the bilateral internal auditory meatus.This was considered to be the route of the cerebrospinal:Huid gush.