The authors present three clinical cases of demyelinating diseases associated with MOG-antibodies. In the first case of a young adult male patient, the disease first manifested with stem encephalitis and high titer of plasma MOG-antibodies. In the second case of a male adolescent, the disease proceeded as neuromyelitis optica, aquaporin-4 antibody titer was normal. In the third case, the female child the disease presented with unilateral multifocal encephalitis and focal epileptic seizures. The article emphasizes the relationship of MOG-antibody titers with the severity and prognosis of the disease.