One hundred sixty-three IUD acceptors over the age of 34 at the time of insertion of the device were compared with 321 IUD acceptors under the age of 35 at the time of insertion. The older IUD acceptors were less educated, more likely to be married, and had more children and more induced abortions. At the time of last follow-up, 161 women were 40 years of age or older, and 323 were less than 40 years old. During 9 years of observations, there were fewer IUD removals and fewer side-effects during the last year of use in the older group of women. Questions relating to the risks of long-term IUD use and the use of hormone-releasing IUDs in this age group remain unanswered.