Objective: To compare the characteristics of recurrent optic neuritis (RON) in multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD). Methods: Seventeen MS and 24 NMOSD patients with RON were retrospectively analyzed in Baoding First Central Hospital. The recurrence rates of ipsilateral ON between MS and NMOSD were compared. Results: There was no significant difference in age, gender, numbers of ON events and incidence of optic disc edema between MS and NMOSD (P>0.05). Both 2 groups presented more frequently with unilateral involvement at their first ON attack (94.12% vs 87.5%, χ2=0.495, P=0.629). Compared with MS, NMOSD patients showed a higher frequency of bilateral eyes involved at the final course (85.33% vs 35.29%, χ2=0.495, P=0.02) and the vision impairment was severer in NMOSD patients (58.33% vs 29.41%, χ2=4.894, P=0.027). The unilateral ON was more common in MS during the whole course and the recurrence rate of ipsilateral eye in MS was higher than that in NMOSD (70.58% vs 29.16%, χ2=10.15, P=0.009). Conclusion: The characteristics of RON have differs between MS and NMOSD. NMOSD patients tend to have bilateral ON successively while ipsilateral and unilateral ON is more common in MS during the whole course. The recurrence rate of ipsilateral eye in MS is significantly higher than that in NMOSD. Unlike binocular random ON in NMOSD, ON in MS tends to involve the same eye affected in the previous episodes.