Objective To study the effectiveness and side effects of the modified new indomethacin VCu IUD Material & methods It is a randomized multi-center clinical trial. Indomethacin VCu and TCu380A were inserted in 2 000 healthy women in 6 clinical units including urban and rural area from May 1997 to Feb 1998, with 1 000 cases in each group. Follow up time were 6, 12, and 24 month after insertion. Results The clinical characteristics of subjects in two groups were similar. Follow up was completed in 98.25% of cases. The net cumulative continuous rate at 6 month was 95.5% in TCu380A group and 97.5% in Indomethacin VCu group (P<0.05); at 12 month it was 93.79% and 94.78% respectively; at 24 month it was 88.23% and 89.77% respectively. The expulsion rate was higher in T group than in V group during 24 months. Termination due to pregnancy and bleeding or pain was similar in two groups. The occurrence of menorrahgia, prolonged bleeding and abdominal pain was also higher in T group than that in V group during 24 months after insertion. Spotting was more often in T group in 12 month. On the other hand, more subjects complained hypomenorrhea in V group. The total B/S period, average B/S period and the longest B/S period were all longer in T group during 4～6 month after IUD insertion (P< 0.01). The amount of hemoglobin was similar in two groups before IUD insertion. At the end of study, the amount of hemoglobin in T group decreased compared with baseline (P<0.001), and was lower than V group at the same time (P<0.001), while no change was observed in V group. Conclusion Compared with TCu380A, the second generation of indomethacin VCu possess the same contraceptive effect and cumulative continuous rate and lower side effects such as bleeding and abdominal pain. VCu is more beneficial to reproductive health of women, therefore, is worth of clinical application. Objective To study the effectiveness and side effects of the modified new indomethacin VCu IUD Material & methods It is a randomized multi-center clinical trial. Indomethacin VCu and TCu380A were inserted in 2000 clinical women in 6 clinical units including urban and rural area from May 1997 to Feb 1998, with 1 000 cases in each group. Follow up time were 6, 12, and 24 months after insertion. Results The clinical characteristics of subjects in two groups were similar. Follow up was completed in 98.25% of cases. The The net cumulative continuous rate at 6 months was 95.5% in TCu380A group and 97.5% in Indomethacin VCu group (P <0.05); at 12 months it was 93.79% and 94.78% respectively; at 24 months it was 88.23% and 89.77% respectively. The expulsion rate was higher in T group than in V group during 24 months. Termination due to pregnancy and bleeding or pain was similar in two groups. The occurrence of menorrahgia, prolonged bleeding and abdominal pain was also higher in T group than t On the other hand, more subjects complained hypomenorrhea in V group. The total B / S period, average B / S period and the longest B At the end of the study, the amount of hemoglobin in T group decreased from 4 to 6 months after IUD insertion (P <0.01). The amount of hemoglobin was similar in two groups before IUD insertion. Compared with baseline (P <0.001), and was lower than V group at the same time (P <0.001), while no change was observed in V group. Conclusion Compared with TCu380A, the second generation of indomethacin VCu possess the same contraceptive effect and cumulative continuous rate and lower side effects such as bleeding and abdominal pain. VCu is more beneficial to reproductive health of women, therefore, is worth of clinical application.