Objective To observe the Effect of OPRM1, A11G genetic polymorphism on the postoperative patient controlled analgesia with sulfentanyl in laryngocarcinoma patients.Methods〓120 patients with American Society of Anesthesiologists (ASA) physical status of Ⅱ or Ⅲ were underwent selective laryngocarcinoma radical surgery with general anesthesia. According to the genotype of OPRM1A118G, the patients were divided into wild homozygote group, heterozygote group and mutation homozygote group. General anesthesia was induced with target controlled infusion of propofol, initial plasma target concentration of 3ug/ml, increased at 0.2ug/ml until the patient's unconscious, following intravenous injection of sulfentanyl 0.2 μg·kg1 and rocuronium 0.6 mg·kg1. Inhaled sevoflurane was at 2%~3%, remifentanil was continuously infused at 0.2 μg·kg1·min1 were used for maintenance of anesthesia. Inhalation concentration of sevoflurane was regulated by monitoring the Narco Trend (NT) value and kept this value between 40-60. Sulfentanyl patient controlled analgesia(PCA) was provided postoperatively for satisfactory anesthesia. The analgesic solution of PCA contained sulfentanyl 100ug and tropisetron 5mg in 100ml of normal saline was programmed to give a 04ml bolus does with a 15min lock out time and background infusion at a rate of 1.0 ml/h maintaining the visual analogue scale(VAS) less than or equal to 3 points is effective for analgesia treatment. The sulfentanyl consumption within 24 and 48 hours after operation and so as the incidence of any adverse reactions were recorded. Results-There was no significant difference in general condition among the three groups.Compared with A/A and A/G groups,the amount of sulfentanil consumed within 24 and 48 hours after operation was significantly increased in G/G group(P＜0.05),but there was no significant difference in the amount of sulfentanil consumed within 24 and 48 h after operation between A/A and A/G groups.Conclusions OPRM1,A118G genetic polymorphism is one of the genetic factors contributing to individual variantion in patientcontrolled intravenous analgesia with sulfentanil in the patients undergoing laryngocarcinoma radical surgery.