Posttraumatic syringomyelia is an uncommon but significant late complication of spinal cord injury. It occurs in approximately 1.1 - 3.2% of cases of spinal injuries. With the increasing availability of CT and magnetic resonance imaging (MRI), the incidence of posttraumatic syringomyelia is increasing. The purpose of this report is to show MRI of posttraumatic syringomyelia and to assess the results of surgical treatment. Materials and Methods This series included 16 cases of posttraumatic syringomyelia studied with MRI. 9 out of 16 cases showed delayed deterioration of neurological symptoms following spinal injuries. The interval between the trauma and the delayed symptoms of deterioration was from 2 years 2 months to 32 years (mean, 8 years and 5 months). There were 13 men and 3 women. The age ranged from 22 to 69 years, with a mean age of 42 years. The initial spinal cord injury was located in the lower cervical region in 4 cases, the thoracic region in 8, and the upper lumbar region in 4. All the patients were studied with resistive 0.15T system (Toshiba MRT 15 A) or a superconductive 0.5T system (Toshiba MRT 50 A) or a superconductive 1.5T system (GE Sigma or Siemens Magnetom). Six patients underwent 8 operative procedures for posttraumatic syringomyelia. Syringoperitoneal shunt was performed in 4 patients, syringosubarachnoid shunt in 3 and ventriculoperitoneal shunt in one. Results 1. MRI In all cases, the posttraumatic syringomyelia was easily diagnosed by MRI. The syrinx extended superiorly and/or inferiorly from the area of the old trauma. In 4 out of 16 cases, the syrinx extended into the medulla oblongata.(ABSTRACT TRUNCATED AT 250 WORDS)