Postpartum insertion of the intrauterine device (IUD) can provide an effective and convenient means of contraception. As a result, the use of IUD's has steadily increased, and the Family Planning Program recommends it because it offers many advantages. However, a major risk associated with the use of IUD's is the possibility of its expulsion, which ranges from 4 to 60%. Furthermore, 20% of women who expelled IUD's were unaware that it occurred, thus increasing their susceptibility to unwanted pregnancies. IUD's modified by the addition of biodegradable strands of chromic suture at time of implantation are thought to be less likely to be expelled, as the sutures anchor the IUD more firmly to the endometrium, and it is possible that the use of these sutures may decrease the risk of expulsion. Therefore we determined if the chromic extension to IUD enhance retention and decreased the rate of expulsion. In one year of study, 150 women received a modified IUD (TCu 380) with chromic catgut number 0 (ccO) in the transversal arm within 10 minutes of delivery of the placenta. However, only 84 women completed the follow-up study. To evaluate IUD expulsion, exploratory examinations were conducted during the immediate postpartum, at 7 days postpartum and at 6 weeks after delivery. We determined the presence or expulsion of the IUD in these three periods postpartum. Other parameters such as parity, age and marital status were also considered. A total of 14 modified IUD's (16.6%) were expelled. This represents a similar frequency of expulsion both during the immediate postpartum and the 7 days postpartum period. There was no significant difference in the rate of expulsion between the two periods. Moreover, there was no expulsion at 6 weeks postpartum. The primiparity women had the highest percentage of expulsion (22.8%). Single mothers either living with or without their sexual partner had expulsion rates of 20.6 and 20.5%, respectively. The highest rate of expulsion when we considered age was in women younger than 30 years of age. There was only one case of expulsion where the mother was unaware of its occurrence. The results described here indicate that age, parity and civil status have no direct influence on expulsion of modified IUD's with chrome extensions. In all postpartum periods studied the p-value was greater than 0.05. Six weeks postpartum was the only time at which there was no IUD expulsion. This is most likely a consequence of decreased uterine cavity size and closure cervix. The modified IUD TCu 380 with chrome strands shows a rate of expulsion similar to other modified IUD's as evidenced in the literature. However, there is a lower rate of expulsion than in unmodified IUD's. It is an important to rote that incomplete expulsion of modified IUD's in this study was considered a total expulsion which represent loss of contraceptive effectiveness. On the contrary, if we had considered only completely expelled IUD's in this study, the percentage would have been significantly lower, as only one total expulsion was found. Further studies are necessary to investigate consecutive expulsions of the TCu 380 modified IUD.