Sudden deafness is defined as an isolate entity of abrupt onset of sensorineural hearing loss without definitive cause and it frequently is accompanied by tinnitus and vertigo. Of many theories for pathogenesis of sudden deafness, disturbance of cochlear blood flow is supported by many investigators but no one knows the definitive cause. Therefore the treatment is difficult, however the authors recently experienced seven cases of sudden deafness with full or partial recovery using low molecular weight dextran, long acting steroid, vasodilator and vitamin B. Our conclusions are as follows : 1) The pathogenesis of sudden deafness was strongly suspected as disturbance of cochlear blood flow and we thought that our treatment method was effective. 2) The earlier the treatment was began the better the recovery of hearing acuity was gained. 3) The prognosis was poor in the case of sudden deafness associated with dizziness. 4) Generally the recovery of hearing acuity was poor in high frequency range.