Objective To investigate the effect of dexmedetomidine combined with ulinastatin on postoperative delirium in elderly patients undergoing resection of gastrointestinal tumor. Methods A total of 180 elderly patients (97 males,83 females,aged 65-80 years,ASA grade Ⅱ orⅢ)who underwent laparoscopic surgery for gastrointestinal tumor,were randomized into four groups (n =45 each):dexmedetomidine group (group D),ulinastatin group (group U),dexmedetomidine+ulinastatin group (group DU)and control group (group C).Patients in group D were given a loading dosage of dexmedetomidine 0.5 μg/kg intravenously 1 5 min before the induction of general anesthesia,followed by a continuous infusion of 0.3 μg·kg-1 ·h-1 ,and dexmedetomidine was ad-ministered till 40 min before the end of surgery.Patients in the group U were given a loading dosage of ulinastatin 10 000 U/kg intravenously in 20 min.In group DU,dexmedetomidine and ulinastatin were administered in accordance in group D and group U respectively.Patients in group C were given 0.9% saline solution.The volume of blood loss,the time of operation and recovery,the adverse reac-tions after surgery were recorded.The concentration of dopamine (DA),adrenaline (AD),norepi-nephrine (NE)were measured within the preoperative 1 d (T0 ),within the first hour of surgery (T1 ),within the postoperative 1 d (T2 ),2 d (T3 ),3 d (T4 ).The confusion assessment method Chi-nese reversion (CAM-CR)was used to screen POD on T0 ,T2-T4 .Results The levels of DA,AD and NE in the group C and group U at T1-T4 significantly elevated than those at T0 (P <0.05);the levels of DA at T1 and the levels of AD at T1 ,T2 in group D and group DU significantly elevated than those at T0 (P <0.05).The levels of DA,AD at T3 ,T4 and the levels of NE at T1-T4 in group D and group DU were significantly reduced compared with those in the group C and group D (P <0.05 ). Compared with the group C,the incidence of POD was significantly reduced in the group D,group U and group DU (P <0.05).Among the three groups (D,U and DU),the difference were not statisti-cally significant in the incidence of POD.Conclusion Dexmedetomidine or ulinastatin may reduce the rate of POD in elderly patients undergoing laparoscopic surgery for gastrointestinal tumor.Compared with the administration of ulinastatin or dexmedetomidine alone,combined application of dexmedeto-midine and ulinastatin does not reduce the incidence of POD.