Background: The neurological outcome and predictive factors of idiopathic optic neuritis (ION) in China are largely unknown. Objective: The aim of this paper is to study the neurological outcome of Chinese ION and to investigate the early predictors for multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD). Method: Retrospective medical record review and supplementary follow-up of 107 ION patients was performed. Statistical analysis of the baseline characteristics as risk factors for ION patients converting into MS or NMOSD was performed. Results: With an average disease course of 9.5 years, 19 of the 107 (17.7%) ION patients developed either MS (9, 8.4%) or NMOSD (10, 9.3%). The estimated 5-year and 10-year combined accumulative risk rates were 14.1% and 26.0%, respectively. Significantly higher estimated accumulative conversion risk was found in female versus male (P = 0.047), adult versus children (P = 0.032), patients with brain MRI lesions versus patients without leasions (P = 0.026), patients with CSF positive oligoclonal bands and/or elevated IgG index versus without (P = 0.003) and patients with poor visual recovery versus patients with good recovery (P = 0.007). Furthermore, brain white matter lesions and good visual recovery were statistically more common typically in MS converters compared with the NMOSD converters (P = 0.01 and P = 0.006, respectively). Conclusion: The combined conversion rate for ION to MS/NMO in Chinese population was lower than the reported rate for Western countries. In addition to some previously reported high risk factors, white matter lesions on the brain MRI at baseline and good visual recovery were found to be good predictors for Chinese ION converting into MS whereas poor visual recovery with a normal brain MRI suggested a higher likelihood of the ION converting into NMOSD. (C) 2014 Elsevier B.V. All rights reserved.