To review our current knowledge of the pathogenesis of sudden sensorineural hearing loss, including viral infection, vascular occlusion and immune system-mediated mechanisms, and to discuss the pathogenesis as it relates to pharmacotherapy.Relevant publications on the pathogenesis of sudden sensorineural hearing loss from 1944 to 2010 were analysed.Sudden sensorineural hearing loss is defined as hearing loss of 30dB in three sequential frequencies over 3days or less. It can be an isolated symptom or the presenting symptom of a systemic disease. The aetiology and pathogenesis remain unknown. Detailed investigation typically reveals a specific cause in about 10% of patients. Proposed theories of causation include viral infections, vascular occlusion and immune system-mediated mechanisms. A variety of therapies have been proposed based on the various proposed aetiologies.