A description is given of the syndrome of post-traumatic syringomyelia amongst patients with traumatic spinal injuries seen at the National Spinal Injuries Centre. The diagnosis was made on clinical grounds. It was confirmed wherever possible by neuroradiology prior to surgery; one case was confirmed only at post-mortem. The incidence of the condition was found to be in keeping with other large series but, in contrast, no difference was found between the time of onset after injury between complete and incomplete lesions of the spinal cord. The commonest manifestation was pain, followed by sensory loss and rarely motor weakness. In the majority of patients the condition eventually became bilateral and in a significant number the lesion ascended to involve the trigeminal territory. The natural history of the condition was followed, and in all cases the condition gradually progressed. The pathogenesis of the condition is briefly discussed in view of the findings.