Abstract：【Objective】To investigate the change of spinal pro?inflammatory cytokines in a rat model of fentanyl induced acute hyperalgesia。【Methods】64 male SD rats were divided into 2 groups（n=32），fentanyl group and NS group. The rats were subcutaneously injected with fentanyl（60 μg/kg） or normal saline（1.2 mL/kg） 4 times with 15 ? minute intervals. Mechanical nociceptive thresholds and thermal nociceptive latency were measured via the tail pressure test（Tail flick thresholds，TFT） and paw withdrawal test（Paw withdrawal latency，PWL）on the day before，at 1，2，3，and 4 hour and on 1~5 day after injection. 4 rats were killed concomitantly and the lumber spinal cord were harvested to analysis the expression of NF-κB，PGE2，TNF-α，IL-1β，and IL-6. 【Results】There were no significant changes of TFT，PWL and the expression of spinal inflammatory cytokines such as NF- κB， PGE2，IL-1β，and TNF-αcompared to baseline of rats treated with normal saline. The value of TFT ，PWL in fentanyl group raised to the highest（above the baseline）at the 1st hour after fentanyl injections and decreased thereafter，reached the lowest at the 1st day， raised increasinglyand up to baseline on the 3 day after injection. NF-κB，PGE2，IL-1β，and TNF-αincreased at the 4th hour，on 1 and 2 day and IL-6 increased at the 4 hour and onthe 1 day after fentanyl injections.【Conclusion】Subcutaneously injection of fentanyl induced significant mechanical and thermal hyperalgesia and increased spinal pro ? inflammatory cytokines parallelly， indicated that fentanyl induced acute hyperalgesia is associated with spinal inflammatory reaction in rats.