Electronystagmography gives objectivation and documentation to the clinical vestibular otoneurological tests. With fixation eliminated the duration of calorically and rotatory induced nystagmus is 30 per cent longer and the eyespeed in the slow phase of this nystagmus up to ten times that recorded under Frenzel's glasses. In a large series of patients only one out of ten cases of spontaneous or positional nystagmus recorded behind closed eyelids could be observed directly. At an acute onset of vestibular symptoms the visual influences are negligible, if the onset is insidious or the interval between onset and examination is longer this visual inhibition is more pronounced. It is a reasonable safety requirement that the same examiner should be equally well orientated in both the audiological and vestibular function tests. The diagnosis of a central vestibular lesion cannot be established until the possibility of the findings being of peripheral origin has been excluded. This latter conclusion usually has to be based on the audiological findings. Calorization yields more from the diagnostic aspect than a rotatory test. After comparing calorigrams and cupulograms in 5,000 patients, this rotatory test was dropped. The experiences of electronystagmography from the diagnostic point of view in 30,000 patients are summarized.