The diagnosis of multiple sclerosis in children and adolescence should be differentiated from a group of rare white matter diseases, with fuzzy diagnostic criteria. Some of these conditions require modern diagnostic techniques and wide knowledge of the doctor. The Moscow Division for treatment of children and adolescents with multiple sclerosis is a specialized advisory structure, which has specialists with experience in the differential diagnosis of multiple sclerosis with pediatric onset. The emphasis on the clinical aspects in differential diagnosis of early onset multiple sclerosis can reduce the time for the diagnosis and help to avoid diagnostic mistakes.