Use of IUDs was examined among 962 women whose pregnancy was terminated at the University Hospital of Trondheim, Norway during 1983. Ectopic pregnancy was significantly more often diagnosed among women with an IUD in place at conception compared to non-users (7.8% vs 1.3%, p less than 0.01). Despite removal of the IUD during the first trimester, women who became pregnant with an IUD in situ had spontaneous abortion more often than non-users (15.6% vs 7.0%, p less than 0.05). The causal significance of these findings will require further investigation. The small number of ectopic pregnancies subsequent to an IUD contraceptive failure in relation to the number of all pregnancies within the same time frame may explain the lack of a demonstrable link between increasing IUD use and increasing rates of ectopic pregnancy.