The effect of betahistine compared with cinnarizine on induced vestibular nystagmus was evaluated using a rotating chair, in 6 healthy volunteers. The subjects underwent a slow acceleration followed by a sudden stop. Electronystagmograph tracings were taken initially as pretreatment control values, and after betahistine 8 mg t.i.d. and cinnarizine 15 mg t.i.d. had been taken. The duration of nystagmus and average eye speed were measured. No difference was recorded in either parameter between the pretreatment rotation and that following betahistine (P greater than 0.05). A significant difference (P less than 0.05) was seen in the duration of nystagmus during initial acceleration, and in average eye speed following the sudden stop after treatment with cinnarizine.