Abstract: Objective: To assess the analgesic and side effects of postoperative intravenous analgesia of radical mastectomy with lornoxican and fentanyl.Methods: Eighty grade Ⅰ-Ⅱ ASA patients of radical mastectomy were randomly divided into two groups:group L(n=40)received post operative intravenous analgesia with lornoxican and fentanyl while group T(n=40) received postoperative intravenous analgesia with tramadol.In group L,lornoxican 56 mg,fentanyl 0.3 mg and granisetron 3 mg were diluted with normal saline to 100 ml while in group T tramadol 800 mg and Granisetron 3 mg were diluted with normal saline to 100 ml.The patients received a loading dose,Group L:lornoxican 8 mg;group T:tramadol 100 mg,before suturing skin and then received the analgesia pump.Pain score(VAS 0-10),sedation score(0-3) and side effects were recorded at 4 h,8 h,12 h,24 h and 48 h after operation.Results: There was no significant difference in pain and sedation scores between the two groups(P>0.05).The incidence of side effects in Tramadol group was higher than that in lornoxican and fentanyl group(P<0.01-P<0.05).Conclusions: lornoxican and fentanyl are safe and effective in the treatment of postoperative pain of radical mastectomy,and have fewer side effects than Tramadol.