The MRI examinations of seven patients with acute transverse myelopathy (ATM) were analysed. The patients were examined 2-5 times during the course of their disease with short and long TR/TE spin-echo sequences in the sagittal projection. A previous history of autoimmune disorder and/or signs of infection at the onset of ATM were present in all cases. Cerebrospinal fluid analysis showed local synthesis of immunoglobulin in the nervous system in three cases and signs of infectious myelitis in one. During the acute phase four patients had local enlargement of the cord and all had increased signal on long TR/TE sequences. The outcome was grave in the majority of patients and there seemed to be a correlation between the degree of cord enlargement, persistence of increased signal intensity and limited recovery. Atrophy and remaining high signal intensity were noted on late MRI in patients with poor outcome. In one patient with probable anterior spinal artery occlusion, cavitation of the cord was seen.