Abstract: Objective:To observe the influence of different dosages of naloxone on morphines postoperation analgesia efficiency in elder patients.Methods:One hundred and twenty elder patients who received intravenous-inhalation combined anesthesia for abdominal operation were randomly divided into 4 groups,30 in each group.Group A:morphines dosage was 10 gkg-1h-1,which was diluted by sodium chloride injection to 100 ml.Group B:0.1gkg-1h-1 dosage of naloxone was added on the base of group A.Group C:0.2 gkg-1h-1 dosage of naloxone was added on the base of group A.Group D:0.3gkg-1h-1 dosage of naloxone was added on the base of group A.Analgesia mode:background infusion(2 ml/h) with patient controlled analgesia(1 ml),lock out time 15 min.Pain visual analogue scale(VAS),nausea and vomiting,pruritus and breath depression were recorded at the time of 2,6,12,24 and 48 hours after analgesia was begun.Results:Analgesia efficiency:VAS was no statistical significances at the same time point between group A,B and C.VAS was raisen at the time of 2,6,12,24 and 48 hours after analgesia was begun in Group D compared with group A,B and C.There were significant differences(P0.01).The scores of nausea and vomiting,pruritus at the time of 6,12,24,48 hours in group B,C,D and at the time of 2 hours in group D were decreased compared with group A,there were significant differences(P0.01).No breath depression was recorded in group A,B,C and D.Conclusions:Naloxone combined with morphine in postoperation analgesia for elder patients can relief the nausea and vomiting,pruritus effectively.Naloxone at 0.3 gkg-1h-1 will resist the analgesia efficiency of morphine.