ObjectivesThe objectives of this article are to review the physiology of hearing; identify acute pathologic and perceived causes of hearing loss in the adult critically ill patient; and to discuss its evaluation, treatment, and prevention.Data SourcesComputerized bibliographic search of MEDLINE from 1966 to the present of all relevant articles in all languages on acute hearing loss in the adult population.Data ExtractionData gathered from studies and reports of acute hearing loss as relates or potentially relates to the periintensive care unit (ICU) period.Data SynthesisHearing loss is an infrequent but potentially serious complication associated with critical illness. The causes of hearing loss in the ICU patient include mechanical or accidental trauma, administration of ototoxic medications, local or systemic infections, vascular and hematologic disorders, autoimmune diseases, and environmental noise. Patients who are elderly, have coexisting liver or renal failure, or who are receiving concomitantly administered ototoxic drugs are particularly at risk for developing hearing loss. A thorough assessment of potential causes of hearing loss and audiological examination should be undertaken on all ICU patients suspected of hearing loss. Mechanical, pharmacologic, and environmental strategies are available to decrease the incidence of hearing loss in this patient population.ConclusionsHearing loss should be recognized as a potential clinical problem by intensivists. Its causes should be identified and appropriate evaluation and therapy initiated. High risk populations should be identified for preventive measures. (Crit Care Med 1999; 27:211-219)