Quinine is a protoplasmotic poison which, in cases of cinchonism, produces tinnitus, hearing loss, dizziness, blurring of vision, photophobia, and hypotension. Administration of a large dose may produce delirium, unconsciousness, respiratory failure, and death. Ototoxicity of quinine seems to be the result of administration of a large dose or prolonged treatment, or it may be a matter of idiosyncrasy. Hearing loss of conductive type is said to occur, by Falbe-Hansen,1 after several clinical and experimental observations, while Forbes2 and Rüedi et al.3 believed it is of perceptive type. The opinions concerning the location and nature of cochlear lesions as observed in experimental animals may be divided in two groups. The first group claims that quinine produced changes in the primary cochlear neurons and hypotonic degeneration in the cochlear receptor. The features and explanation of this phenomenon were put forward by Wittmaack,4 and have been supported by