OBJECTIVE: To prove that the skin of paralysed limb of spinal injured rat is more susceptible to a thermal injury than control, and to find out that the possible relating factors for explaining the increased susceptibility of skin. METHOD: Of total 69 male Sprague-Dawley rats, 50 were randomly divided into two groups, the spinal injured of which cords were transected at T10-13 level and the control. They were subdivided into 5 subgroups according to the duration of thermal injury. Infrared ray was used for thermal injury. Arterial cannulation was done in the femoral artery for blood gas analysis. Temperature was measured with a digital thermometer. Biopsy samples were stained with HE, and also immunohistochemical staining for heat shock protein 70 (HSP-70) was done. RESULTS: After thermal injury, the spinal injured group showed more severe tissue damage and a higher temperature elevation than the control. There was a tendency of decreased blood pH and pO2, and increased pCO2. Contrary to the control, the immunoreactivity of HSP-70 was very tiny or rarely present in the spinal injured group. CONCLUSION: This study suggest that the increased susceptibility of skin to the thermal injury in spinal injured rats may be related to the vasomotor instability. And, the poor expression of HSP-70 from the skin of spinal injured rat can be a factor for the explanation of the defective cellular protective response in spinal cord injury.