Objective To evaluate the effectiveness and safety of Misoprostol,Prostaglandin E2 suppositories and COOK balloon catheter in induction of labor at term.Methods 91 women of full-term pregnancy with indications of induced abortion,and cervical Bishop score <6 were randomly divided into Misoprostol group (31 cases),Prostaglandin E2 group (32 cases) and COOK balloon group (28 women).The improvement of cervical conditions was compared before and after the application.The uterine contraction,labor time,fetus delivery method,situation of maternal and newborn were determined.Results The obvious effective rate in Prostaglandin E2 suppositories was 78.6%,in COOK balloon group it was 75.0%,both were significantly higher than those in Misoprostol group.However,the side effect such as placental abruption was found in Prostaglandin E2 group.The cesarean section ratios in the COOK balloon group and the prostaglandin E2 group were much the same,but both were lower than those of the Misoprostol group.Conclusion Although the efficacy of Misoprostol is much weak,it is convenient and cheap.COOK balloon catheter method is the same as prostaglandin E2 in induced labor at term,it is safe and has less side effect. Key words: Misoprostol; Prostaglandin E2; COOK balloon catheter; Induction of labor at term