Objective To evaluate the efficacy of flurbiprofen axetil for treatment of break-through pain (BTP) in patients with metastatic bone cancer pain.Methods Ninety-seven patients with metastatic bone cancer pain complicated with BTP were randomly divided into morphine group (M group,n =51) and flurbiprofen axetil group (F group,n =46).In group M,immediate release morphine sulfate was given orally,and the single dose for pain relief was about 10％ to 15％ of the daily slow-release dose,and the administration was repeated until BTP was relieved.In group F,flurbiprofen axetil 50 mg was infused intravenously over 30 min,and the maximum dose was 150 mg.The BTP frequency was recorded within one month after the first BTP relief.The drug consump-tion for treatment of primary cancer pain,and adverse reaction were recorded.Results The onset time of flurbiprofen axetil and immediate release morphine sulfate was (18± 9) and (35± 11) min,respectively (P ＜ 0.05).The onset time of BTP treatment was significantly shorter,and the incidence of constipation was lower in group F than in group M (P ＜ 0.05).There was no statistical significance in the BTP frequency between the two groups (P ＞ 0.05).As compared with that before BTP treatment,the drug consumption for treatment of primary cancer pain was significantly increased after treatment in group M (P ＜ 0.05) and no significant changes were found after treatment in group F (P ＞ 0.05).Conclusion Flurbiprofen axetil is safer and more effective in relieving BTP in patients with metastatic bone cancer pain than immediate release morphine sulfate,and it does not affect the drug tolerance for treatment of primary pain.