Opiate receptor agonists (especially dynorphin - a kappa receptor agonist) have found to increase in the injuried segment of spinal cord. It is known to cause spinal cord damage when injected intrathecally. Nalbuphine is a kappa opiate receptor agonist/partial mu antagonist, and fentanyl is selective mu receptor agonist. To determine the effect of nalbuphine and fentanyl on experimental spinal cord injuries of Spague-Dawley rats (N=125): 1) I determinded the MAC (or ED50) values of enflurane, fentanyl, nalbuphine-enflurane in 65% N2O; 2) produced spinal cord injury model by different epidural ballooning time in the control (enflurane) gmup ; 3) produced spinal cord injuries in the experimental (fentanyl, nalbuphine-enflurane) group. The results were as follows ; 1) The MAC value of enflurane was 1.16+/-0.05%, and the ED50 values of fentanyl were 26.8, 36.2, 39.7, 44.7 ug/kg after 15, 30, 45, 60 min of injection, respectively. Also the MAC values of enflurane with 20 mg/kg nalbuphine were 1.08, 0.99% after 60, 90 min of injection, respectively. 2) We produced the graded spinal cord injuries by different epidural ballooning time. 3) The total neurological scores of fentanyl experimental group were significantly higher than control group on the 10th, 14th, and 21st postinjury day.