Ten workers struck by the same blast of an explosion were selected for a comparative study: 5 patients were treated with low molecular weight dextran, 5 patients were left without treatment. Recovery from the inner ear damage, measured by the restoration of hearing losses (bone conduction threshold), proved significantly better in the treated group. This result supports the concept that microcirculatory disturbances in the cochlea play an important role in the pathogenesis of permanent hearing loss after exposure to damaging noise intensities.