We reviewed the clinical and neuroradiological features in 16 patients with serious neurological complications of lumbar epidural anaesthesia. We observed acute, transient or permanent and delayed complications. Four patients had symptoms immediately after the procedure. One patient developed a subacute flaccid paraparesis. Two other patients had infectious spondylodiscitis at lumbar puncture level. Eight patients had a delayed progressive spastic paraparesis and were found to have subarachnoid cysts and irregularities of the surface of the spinal cord consistent with arachnoiditis; six of them had an extensive, complex syrinx within the cord. One patient had a severe lumbar polyradiculopathy, and MRI showed adhesive arachnoiditis involving the cauda equina. Although epidural anaesthesia is generally considered safe, rare but severe complications, such as radiculopathy, infectious disease, myelopathy from ischemia and arachnoiditis with a syrinx may occur. The patients with arachnoiditis had a relentless progression of the disease and a poor outcome: five are confined to a wheelchair, one is bedridden. Complications of epidural anaesthesia are easily recognised when they develop immediately; their relationship to the anaesthesia may be ignored or underestimated when they appear after a delay. Awareness of the possibility of delayed complications is important.