Intrauterine devices (IUDs) were applied in 554 women during cesarean sections and the results were compared with the event rates presented in 804 women who received the IUD vaginally immediately postpartum. The expulsion rates at one month were 4.1 for the IUD inserted during the cesarean section and 7.5 for the post partum IUD. The expulsion rates at three months were 10.9 and 16.4 respectively. In a third group of 240 women who had cesarean sections but did not accept the IUD for contraception, the rate of endometritis at one month resulted in 0.8 compared with 1.1 for the group of cesarean section with IUD. Almost two thirds of the cesarean sections in both groups were performed on emergency bases. The application of the transcesarean IUD is considered to be safe procedure for fertility control.