In persons suffering from occupational pathology due to antibiotics, the clinical picture of neurosensory hypoacusis is described and the pathogenetic mechanisms of the illness are unraveled. Perceptive bradyacusia occurs in the presence of organic pathology of the nervous system, internal organs and skin. In addition to the toxic action, antibiotics exert an allergenic action. As a result there develops allergic cerebral vasculitis. The latter one is an additional pathological factor giving rise to neurosensory hypoacusis in occupational pathology induced by antibiotics. The data obtained can be used in administration of pathogenetic therapy and in expert medical evaluation of the working capacity.