Background and purpose: Cortisol has neuroprotective effects. We monitored the serum cortisol levels after cervical and thoracic spinal cord injury (SCI) in four groups of rats. Materials and methods: Forty male Sprague-Dawley rats were randomized to four groups. The control group received neither laminectomy nor SCI. The sham group received laminectomy without SCT. The cervical spinal trauma group received a C5-C6 laminectomy and spinal trauma at this level. The thoracic spinal trauma group received a T6-T7 laminectomy and spinal trauma. Blood samples were drawn 2, 6, 12 and 24 hours after surgeries and assayed immediately.