Effects of two types of intrauterine device (IUD) on the prostaglandins and endothelin (ET) in uterus and on the endometrial morphology in rats and rabbits, and Cu2+ releasing amounts of both IUDs in vitro were observed. The results showed that the inhibiting action of the indomethacin-releasing copper IUD (FICu-IUD) on the PGI2 was stronger than that on the TXA2, the ratio of 6-keto-PGF1α/TXB2 was reduced with the increase of the doses. There were significant differences between the groups. The FICu-IUD could inhibit the rising of the ET level and lighten the endometrial impairment caused by the FCu-IUD, and promote copper ion release. It was suggested that indomethacin released by FICu-IUD could effectively reduce abnormal uterine bleeding.