Background: To study the role of spinal alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptors in pain behaviors caused by mild bum, we examined the effect of intrathecal administered ACEA 2085, which has been recently characterized as a high potency competitive AMPA receptor antagonist, on the thermal hyperalgesia state induced by mild burn. Methods: A thermal injury was induced by applying the left hind paw to a thermal surface (52.5C) for 45 sec, Thermal escape latency of the hind paw was determined using an underglass thennal stimulus. Thirty min after thermal injury, the paw withdrawal latency (PWL) in injured paw of all groups fell from 10-12 sec to 5-7 sec. At that time, ACEA 2085 (0.01-0.1 mcg) and 6-cyano-7-nitroquin- oxalinedione (CNQX, 1-30 mcg) were injected through intrathecal catheters in rats with mild burn injury on the right hindpaw, And then, PWL were measured in the both hindpaw every 30 minutes for about three hours. Results: The intrathecal injection of ACEA 2085 produced a dose dependent reversal of the hyperalgesia in the right hindpaw and more potent than CNQX, but had no effect upon the response latency of the normal left hind paw even at the largest doses. All effects were observed at doses that had no significant effect upon motor function. Conclusions: Intrathecal ACEA 2085, highly selective AMPA receptor antagonist produce a dose- dependent reversal of the thermal hyperalgesia evoked mild burn injury. These results suggested that spinal AMPA receptor play an important role in the hyperalgesia induced by mild burn injury.