Eighteen patients with posttraumatic paraplegia were examined myelographically at 2 months to 30 years after the injury, and the findings correlated with surgical exploration. The following six myelographic patterns were seen: 1) tethered cord and subarachnoid adhesions; 2) proximal cord cysts; 3) loculated subarachnoid cysts; 4) proximal cord atrophy; 5) extradural fibrosis; and 6) complete obliteration of the subarachnoid space at the level of trauma due to extradural fibrosis and/or bone encroachment on the vertebral canal. Myelography with or without computerized tomography (CT) accurately reflected the gross pathological process. The examination is indicated prior to surgical intervention: the structural lesion in four patients extended two or more vertebral levels above the site of the original bone injury and was not easily predictable preoperatively. When combined with CT, myelography allowed evaluation of the transverse anatomy of the vertebral canal and its contents; it was especially useful when the canal was narrowed or distorted by bone and soft tissue. Water-soluble contrast media provided a more detailed evaluation of the spinal cord and subarachnoid space, and were the preferred agents. If a posttraumatic syrinx is suspected, these are the agents of choice.