In 15 cases, a rupture of the round window membrane could be found via exploratory tympanotomy. The main sign in these cases was an inner ear deafness; vertigo and tinnitus were less frequent. These findings correspond well with reports in the literature. Since there is no specific clinical sign of a ruptured membrane, tympanotomy is necessary in all suspicious cases. Chances of restoration or maintenance of hearing are high in cases of early repair of the fistula, but prospects diminish as the time interval between injury and repair increases. Vertigo and tinnitus disappear even by a delayed operation. The healing process of the round window membrane and the pathological changes in the round window niche after ruptured membrane were studied in guinea pigs. To evaluate the relationship between round window membrane rupture and blunt head injury, 87 temporal bones were studied after a fatal head injury.