Sudden hearing loss and vertigo after physical exertion has been uncommonly experienced clinically as perilymphatic fistula. The physical exertion may increase cerebrospinal pressure. The increased CSF pressure is transmitted to the perilymphatic system through the cochlear aqueduct, to a lesser extent, by way of the endolymphatic sac and duct, and internal auditory canal. This can result in damage of vestibule or cochlea of inner ear, such as a rupture of the round and oval window membrane, a dislocation of the annular ligament of stapes, the rupture of Reissner's membrane and collapse of membranous labyrinth. To clarify the effect of increased abdominal pressure, one of the physical exertions, on the perilymphatic pressure, this experimental study was performed. The following conclusions could be drawn from measurement of the perilymphatic pressure on increased abdominal pressure of Albino guinea pig. 1) The perilymphatic pressure of Albino guinea pig was 2.60±0.21mmHg under the restion state. 2) Increased abdominal pressure caused proportional increment of the perilymphatic pressure. 3) Perilymphatic leakage could be observed following repeatedly increased abdominal pressure.