IT IS THE purpose of this report to discuss the mysterious symptom complex referred to most commonly as "epidemic vertigo." Clinical experiences with 24 cases seen between August 1962 and June 1964, will be discussed and results of a preliminary investigation of possible etiology presented. The syndrome was probably first described by Barré and Reys,1 who referred to it as "vestibular epidemic vertigo." Since then the syndrome has been variously termed "epidemic vertigo,"2 "neurolabyrinthitis epidemica"3"nevraxite vertigineuse,"4 and "acute labyrinthitis." 5,6 In my experience, the syndrome has consisted of acute, usually severe vertigo, associated at times with nausea and vomiting. The absence of other symptoms is often striking, although upper respiratory symptoms are common.7,8 The patient maintains normal hearing and caloric examinations are almost always normal. Headache, fever, and other constitutional symptoms have not been part of the picture. Physical examination has been unremarkable except