The clinical performance of the Copper T 380A (TCu 380A) and the Copper T 220C (TCu 220C) intrauterine devices (IUDs) were evaluated for 12 months in a group of women who had one of the two IUDs inserted. Results are from a randomized clinical trial conducted at four collaborating research sites located in two developing countries. The gross cumulative life-table pregnancy rate of the TCu 380A IUD was found to be lower than that of the TCu 220C IUD at 12 months (0.3 and 0.8, respectively), although this difference was not statistically significant (p > 0.05). Statistically significant differences between the two study IUDs were not found with regard to IUD expulsion or IUD removal due to bleeding/pain, personal reasons, medical reasons, or planned pregnancy. No statistically significant differences were observed in the frequency of experiencing menstrual disturbances (i.e., dysmenorrhea, intermenstrual pelvic pain or intermenstrual bleeding) between the two IUD groups. These data suggest that the TCu 380A and TCu 220C IUDs are both appropriate options for contracepting women. The TCu 380A IUD, however, may be a more appropriate option for those women wishing to space births over a longer period of time.