This study was conducted to evaluate a new and improved inserter (GyneFix) for the anchoring of the Frameless IUD in the uterine cavity. Previous studies conducted with a prototype inserter (Flexigard) did not show fully the advantages of the new anchoring concept because of the shortcomings of the Flexigard inserter and the complexity of the insertion technique. The GyneFix IUD was compared with the TCu380A IUD in six centers in China in approximately 300 women in each group. Only parous women were included in the study. The data from this 3-year, ongoing study demonstrate that the shortcomings of the inserter have been corrected, resulting in better performance and a much reduced rate of failed insertion/expulsion of the frameless and anchored device. The cumulative expulsion rate with the GyneFix IUD was 3.0 at 3 years (annual rates 2.67, 0.33, and 0.0, respectively) compared with a cumulative expulsion rate of 7.38 at 3 years with TCu380A (annual rates 4.63, 1.76, and 1.04, respectively). This difference is statistically significant. The majority of the expulsions with the anchored IUD occurred early in the study, indicating improper anchoring technique. The study also shows that both devices are highly efficacious. No pregnancies occurred with the GyneFix IUD (cumulative pregnancy rate 0.0 at 3 years) versus one pregnancy with TCu380A (cumulative pregnancy rate 0.34 at 3 years). The total use-related discontinuation rate at 3 years was significantly lower with the GyneFix IUD (8.34) than with the TCu380A IUD (14.13) and results in a higher rate of continuation with the GyneFix IUD compared to the TCu380A IUD (90.73 vs 85.25). Neither perforations nor pelvic inflammatory disease cases were encountered with either device in this study, demonstrating the safety of the anchoring system.