We experienced three female patients with sudden sensorineural hearing loss. All the patients showed elevation of anticardiolipin antibody in the serum. Immunoglobulin (Ig) M anticardiolipin antibody was present in case 1 (a 34-year-old woman). IgG anticardiolipin antibodies were present in cases 2 (a 50-year-old woman) and 3 (a 9-year-old girl). The patient in case 1 showed hearing disturbance of low tone in the left ear and normal vestibular function in both ears. The case 2 patient had an average hearing level of 81.7dB at 0.5, 1, and 2kHz and severe canal paresis in the right ear. In case 3 the patient showed an average hearing level of 53.3dB in the right ear and normal vestibular function in both ears. It was suggested that thrombosis which might have been induced by anticardiolipin antibody could have caused the sudden sensorineural hearing loss in these patients. Steroid therapy cured the hearing disturbance completely in case 1. Steroid and prostaglandin E1 therapy did not improve the hearing disturbance in case 2. Steroid, prostaglandin E1, and ticlopidine hydrochloride therapy improved the hearing disturbance in case 3. It appears that not only steroids but also prostaglandin E1 and ticlopidine hydrochloride therapy may be effective in patients with sensorineural hearing loss associated with anticardiolipin antibody.