Transverse myelitis is a disease with various pathogenesis. It leads to a partial or total transverse lesion of the spinal cord structures resulting in an acute or subacute: motor (paralysis or paresis), sensory (most often with sensory level) and autonomic symptoms and signs. Its etiology is complex and sometimes difficult to establish explicitly. The most frequent reason of transverse myelitis is infection, but there are other factors like: postinfectious, neoplastic, paraneoplastic, demyelinating, immunological (connective tissue diseases), vascular and others. Idiopathic transverse myelitis accounts for about 10-40% of cases, and despite thorough diagnostics its aetiology cannot be established. Transeverse myelitis has been known for years, but it still poses a big problem both diagnostically and therapeuthically. Its course is frequently serious leading to persistent neurological damage and permanent disability. Diagnostic methods of choice are spinal cord MRI and CSF examination with assessment of oligoclonal bands, biomarkers of inflammatory process, 14-3-3 protein and neuronal specific enolase. Its treatment is determined by established aetiology. Many inconsistencies, no clear cut definition of the disease and lack of diagnostic criteria are being discussed by the group of experts working in Transverse Myelitis Consortium Group.