Abstract: Objective:To investigate the effects of preemptive analgesia of parecoxib sodium on cellular immune function in perioperative period of patients with esophageal carcinoma.Methods:Fifty patients scheduled for esophageal carcinoma surgery were randomly divided into P and C group.Group P and C were injected with 5 ml of parecoxib sodium(40 mg)and normal saline at 30 minutes before anesthesia induction respectively.Two groups were treated with patient controlled epidural analgesia after operation.The levels of T-lymphocyte subsets(CD4+and CD8+)and T helper lymphocytes differetiation were measured by flow cytometry before anesthesia induction,at 2 hours after the start of operation and 24 and 48 hours after operation.Results:The differences of the levels of CD4+＆ CD8+,Th1 ＆ Th2 and ratio of Th1 and Th2 in two groups were not statistical significance before anesthesia(P0.05).Compared with before anesthesia,the levels of CD4+and CD4+/CD8+in two groups decreased at 2 hours after the start of operation and 24 and 48 hours after operation(P0.01).Compared with group C,the levels of CD4+at 24 and 48 hours after operation and CD4+/CD8+at 2 hours after the start of operation and 24 and 48 hours after operation in group P were higher(P0.05 to P0.01).Compared with before anesthesia,the levels of Th1 and ratio of Th1 and Th2 in two groups decreased at 24 and 48 hours after operation(P0.05 to P0.01),while the Th2 level significantly increased(P0.05 and P0.01).The ratio of Th1 and Th2 in group P was significantly higher than that in group C at 24 and 48 hours after operation(P0.05 and P0.01).Conclusions:Preemptive analgesia of parecoxib sodium may alleviate immunosuppression in tumor patients by the way of lowering the decreasing index of CD4+T lymphocyte,inhibiting the tendency of Th1/Th2 balance and activating Th2 immune response.