The recent knowledge about the effects and the biological roles of prostaglandins(PGs) in the female reproductive system were reviewed on the following view points in detail and the authors also argued on the efficacy and reliability for the induction of labour and therapeutic abortions in midtrimester pregnancy. 1. The actions of PGs on the myometrium in vivo and in vitro and the effects of ovarian hormones on the actions of PGs. 2. The actions of PGs on the fallopian tube. 3. The role of PGs in the initiation of menstrual bleeding and dysmenorrhea. 4. The biological action of PGs on the mechanism of labour and parturition. 5. The efficacy and reliability of PGs for therapeutic abortion in the first and midtrimester pregnancy. 6. The biological role of PGs in the activity and life-span of corpus luteum.