The observation of spontaneous nystagmus is important in diagnosing vertigo. However, in some cases, nystagmus disappears before the first examination. In order to predict nystagmus during an attack of vertigo, a vertigo reproduction video system was devised and used to diagnose vertigo.Regarding horizontal-rotatory nystagmus and rotatory nystagmus, the nystagmus conditions estimated by the vertigo reproduction video system were in accordance with actual nystagmus.A screen possibly corresponding to horizontal-rotatory nystagmus was selected in Meniere's disease cases and that corresponding to true rotatory nystagmus was selected in benign paroxysmal positional vertigo.Patients suffering from vert ebral-basilar circulation insufficiensy showed various types of vertigo.This video system is very useful in making differential diagnosis between Meniere's disease and benign paroxysmal positional vertigo and in judging abnormal sides.