Purpose : To evaluate the prevalence of aquaporin 4 antibody (AQP4-Ab) in the newly onset optic neuritis patients and investigate the characteristics of seropositive patients.Methods : 36 women and six men with newly onset isolated optic neuritis were included in this study between January 2013 and December 2014.AQP4-Ab was detected and all blood samples was obtained prior to treatment and within one week from attack.The patients were sub-grouped into either a seropositive group or a seronegative group according to AQP4-Ab.Differences in age, gender, initial visual acuity, and final visual acuity between groups were analyzed.