The prognosis of SMON [subacute myelo-optico-neuropathy] in those 60 yr old or over is not favorable and there is no prognostic differences between male and female. The cummulative death rate of SMON which was calculated by the life table method is approximately twice as much as the generally expected value. Approximately 80% of the patients showed some sort of improvement 7-12 mo. after the onset of the disease. The rate for 13 mo. or over is nearly the same. The abdominal symptoms found at the time of the onset of the disease decreased markedly in the course of the disease. Among neurological symptoms, the prognosis of motor disorders is more favorable. The patients who were administered clioquinol over a long period displayed a higher rate of severe or moderate motor, sensory and visual disturbances, compared with the group with short-term administration of clioquinol. The death rate was also higher in the former group. The rate of relapse as a whole was 16.7% and 68% of those seen within 18 mo. after the onset. Approximately 65% returned to work in 12 mo. or more after the onset. The employment rate was not different according to sex, whereas it was lower along with advancing age. Approximately 20% did not receive medical treatment. The rate of non-treated patients is higher in the younger patients. The rate of hospitalized patients was higher in the older patients.