We describe a unique case in which a patient was initially diagnosed with meningoencephalitis and then detected anti-myelin oligodendrocyte glycoprotein (MOG) antibody and demyelinating brain lesions. A 43-year-old Chinese man who complained of headache and fever, was diagnosed with meningoencephalitis after cerebrospinal fluid (CSF) analysis. One month after onset, brain imaging revealed multiple lesions in bilateral white matter, and the anti-MOG antibody was detected in his serum and CSF (titer is 1:32 and 1:10, respectively). After a 3-month glucocorticoid therapy, repeated brain imaging and serological analysis for anti-MOG antibodies showed significant improvement. Multiple intracranial demyelinating lesions secondary to meningoencephalitis may be accompanied by anti-MOG antibody positivity, which can be reversed by hormone therapy.