A 30-year-old woman was admitted to our hospital in May 1977, suffering from oscillation, body tremulousness and astasia-abasia. Two months prior to admission she had caught a common cold and felt paresthesia on the right arm. Three days before admission, she had photophobia, tremulousness of the trunk and head, and astasia-abasia. A neurological examination revealed difficulty in standing, and jerky movement of the body and right arm, her limbs were well coordinated. An ocular examination resulted in normal findings except for intermittent oscillation of the eyeballs. As the pupils and fundi were normal, so were the routine laboratory tests. The cerebrospinal fluid was clear and colorless under normal pressure, and showed no more than 6 mononuclear cells in any of the three examinations. CSF protein was registered 20 mg/dl, glucose 75 mg/dl, and no virus titers were elevated. Electroencephalogram was slightly abnormal due to a slowing of the Alpha wave in the background activity. Both computerized tomography and vertebral-angiography were normal. A slow and steady abatement of all symptoms started while she was taking steroid treatment in hospital. Electrooculogram showed irregular disconjugation of the eyes rotating or moving in horizontal and vertical direction. There movements conjugated or disconjugated in both eyes with 5-7 Hz of frequency and 10-20 degrees of amplitude. They decreased when the eyelids were closed or staying in a dark room. These ocular movements were regarded as opsoclonus. Then opsoclonus changed to flutter-like oscillation.(ABSTRACT TRUNCATED AT 250 WORDS)