In 1926, we published from this clinic1 our experience with the vestibular reactions in 116 verified intracranial lesions. In the present contribution, we propose to review the vestibular reactions, especially in pretentorial lesions, with a view to determining whether they present syndromes which would be an aid to localization.2 This series of cases by no means represents the total number which were observed in the clinic and were studied by us. Several thousand patients were examined, but unfortunately many cases were unverified, while others, though verified by autopsy or operation, could not be utilized because the charts were incomplete. The accompanying table shows the number of lesions constituting this series with their location in the respective regions of the brain. For the purpose of more clearly presenting the observations necessary for the diagnosis of a lesion of the brain by means of the vestibular tests, this paper has