Clinical experience with intrauterine devices was evaluated, based on 627 insertions over a 14-year period in a private practice. Overall, there were few differences in the event rates leading to IUD discontinuation for the IUDs evaluated, principally Cu-7, Dalkon Shield and Lippes Loop. Pelvic infections were infrequent (0.7-2.2 cases per 100 woman-years of IUD use). The rate of PID in the study population appeared to be similar to that noted in the general population. IUD use did not appear to compromise future fertility, based on evaluations of patients after removal of their IUDs or from their return to fertility following IUD removal. IUD event rates (pregnancy, expulsion, displacement, removal for bleeding and/or pain) were related to the difference between endometrial cavity length and IUD length. A significant increase in the event rates was noted, regardless of the IUD type, when the endometrial cavity length exceeded IUD length by 2.0 cm or more, or when the difference between the endometrial cavity and IUD length was less than 0.5 cm.