Vestibular reactivity changes on the nonoperated side of the ear after all types of stapes surgery occurred in 89% to 92% of otosclerotic patients. Vestibular excitability contralateral changes in the form of hyperreflexia appeared immediately after operation and were characterized by 10-to 25-second reduction of the latent period, by 25- to 50-second lengthening of total nystagmus duration, by the increase of the total number of beats, and by the amplitude increasing by two to ten and more times. Contralateral changes of vestibular excitability persisted for one to ten days in the majority of patients (in 74% to 76% of patients; it persisted for a month in 18.5% to 21.0% of patients and for six months in 5.0% to 5.5%. In 34% of cases, vestibular excitability increase was accompanied by hearing improvement in the nonoperated ear.