One hundred and ninety-five magnetic resonance (MR) images (1.5 Tesla) of 167 patients with neurological impairment following spinal trauma were reviewed. Acute cord injury produces central haemorrhagic necrosis that extends transversely and longitudinally with time and increased injury severity. Oedoma is more homogeneous, extensive and dominant in minimal lesions. Magnetic resonance appearances correlate with neurological status and outcome. Patients with MR evidence of cord blood had severe clinical lesions and failed to show useful clinical improvement. Patients with homogeneous 'oedema' improved to useful function. Lesion signal inhomogeneity relates to a worse prognosis. The clinical level correlates closely with cord blood or signal in homogeneity but imprecisely with homogeneous oedema. Disc herniations require differentiation from epidural blood and venous engorgement, which are prominent with bone displacement. Magnetic resonance is recommended in incomplete cord syndromes and in cord injuries with no apparent fracture, particularly if clinically deteriorating. Chronic injury consists of cavitation, extensive gliosis, cord atrophy and leptomeningeal fibrosis. Progressive myelopathy may result from cystic or non-cystic intramedullary lesions. Cord cysts are common and cyst fluid signal should closely follow cerebrospinal fluid. Turbulent cyst fluid motion is commoner in larger cysts and may predict those cysts more prone to propagate. Progressive syrinxes show typical appearances, usually with transverse septa. Atrophy and propagating syrinxes usually take years to develop. Leptomeningeal cysts and spinal stenosis caused by bone displacement and accelerated adjacent disc disease may cause late deterioration. In progressive myelopathy following injury, surgically drainable cysts are clearly differentiable from cord gliosis and atrophy.