Abstract: Objective :To observe the treatment and side effects of transdermal fentanyl (Duro-gesic) on moderate and severe cancer pain. Methods : Sixty-six cases of patients with moderate and se-vere cancer pain, without chemotherapy, radiotherapy and osteoclast inhibitors, were analyzed retro-spectively. The initial dose was 25ug/h for the patients with no previous administration of opioids, thepatch was changed every 3 days, another 25ug/h was added if the pain was not relieved satisfactorily.The dose of Durogesic depended on previous use of opioids, if there was. Results : Complete remission30 cases (45.4%), apparent remission 25 (37.8%), moderate remission 5 (7.57%), mild remission 2(3.03%), the total remission rate 90.9%; adverse effects were somnolence in 10 cases (15.1%), nauseain 15 (22.7%), vomiting in 6 (9.09%), dry mouth in 2 (3.03%), constipation in 13 (19.7%) and dysuriain 6 (9.09%); 3 cases were drop-out of the treatment because of severe side-effect (2 nausea, vomiting,1 sleepiness and 15 without any side effect (22.7%). Conclusion : Durogesic, being convenient and safe,is effective for cancer patients with moderate and severe pain.