objective:to observe the effects of lithium chloride(licl)pretreatment on remifentanil-induced hyperalgesia in rats model of incisional pain. methods:fourty-two male sprague dawley(sd) rats were randomly divided into seven groups(n=6):control group(c),incisional pain group(i),remifentanil+ incisional pain group(r),incisional pain+licl group(il),remifentanil+incisional pain+low-dose licl group(rl1),remifentanil+incisional pain+medium-dose licl group(rl2),remifentanil+incisional pain+high-dose licl group(rl3). licl 0.4 ml were administered to il group and rl1~3 groups intraperitoneally ten minutes before anesthesia with sevoflurane,the dose of licl in il group and rl1~3 groups were 36,9,18,36 mg/kg respectively,accordingly saline were administered intraperitoneally to group c,i and r. r group and rl1~3 groups were pumped subcutaneously with remifentanil(40 μg/kg)at the speed of 0.8 ml/h at fifteen minutes after anesthesia with sevoflurane,while group c,i and il were pumped subcutaneously with saline accordingly. all groups except c were made the model of incisional pain. at t0(24 hours before operation)and t1(6 hours after operation),t2(24 hours after operation),t3(48 h after operation)respectively,paw withdrawal thermal latency(pwtl) and paw mechanical withdrawal threshold(pmw) were detected on the rats’ right hindpaw in all groups. results:at t1,t2,t3,the pmw and pwtl were significantly lower in group r and significantly higher in group il then those in group i(p < 0.05). comparing with group r,the pmw and pwtl in rl groups were significantly higher(p < 0.05). conclusion:in rat model of incisional pain,remifentanil could induce hyperalgesia on the area of adjacent to the incision;lithium chloride could increase the pain threshold of incision and prevent the remifentanil-induced hyperalgesia.