PIP: A prospective, randomized clinical trial was conducted to determine the efficacy, side effects, and bleeding patterns of 2 T-formed IUDs, the Progestasert and a copper containing IUD (CuT 200). 196 women were fitted with Progestasert (96 nulli- and 100 multi-parae) and 186 with CuT 200 (99 nulli- and 87 multiparae). Mean age in the Progestasert group was 24.3 years (range 15-44) and mean parity 1.0 (range 0-4). In the CuT 200 group, corresponding figures were 23.7 years (range 15-44) and parity 0.9 (range 0-6). The women were told to keep a menstrual diary card indicating duration and frequency of menstrual bleeding, spotting, and pain. Follow-up clinic visits and gynecological examinations were scheduled at 6 weeks, 6 months, and 12 months after insertion, or earlier if necessary. The Chi-Square test and Student's T-test were used in statistical analysis. 8 women became pregnant, 4 in the Progestasert group (1 nulli- and 3 multiparae), and 4 in the CuT group (1 nulli- and 3 multiparae). In the Progestasert group, 1 pregnancy was ectopic. 9 women were lost to follow-up. No significant differences were observed between the groups in terms of duration or number of intermenstrual bleeding and spotting. There was no significant difference in menstrual pattern between the groups prior to IUD insertions. 12 months postinsertion, duration and heaviness of menstrual bleeding had increased in all groups. In the Progestasert group, duration of menstrual bleeding (mean, 6.80) was significantly longer than in the CuT 200 group (mean, 6.05, p0.05). In the nullipara group, the difference in duration of menstrual bleeding was significant (Progestasert, mean 6.91; CuT 200, mean 6.09 p0.05). No significant difference in duration of menstruation was seen in the para group of women. The heaviness of menstrual bleeding was significantly higher in the CuT 200 group as a whole (p0.05) and in the group of nulliparae with CuT 200 (p0.05). The findings show that CuT 200 is more useful in practice but Progestasert is preferable for women who bleed heavily.