An analysis of the clinical data of 552 patients treated for ectopic pregnancy during 1973-82 in our hospital showed that the prevalence of this complication rose twofold (P less than 0.01) from an annual rate of 10.9 per thousand in 1973 to 20.9 per thousand in 1982. As regards parity distribution, the proportion of the 2-paras increased significantly (P less than 0.05) and this increase was significantly greater (P less than 0.001) than in the total population of parturients during this period. The increasing incidence of ectopic pregnancies had a significant positive correlation (P less than 0.05) with the use of an intrauterine device (IUD), but not with previous or present pelvic inflammatory disease or gynaecological or abdominal surgery. Because the 158 patients with an IUD in situ (34%) had a significantly less frequent past history of salpingitis, pelvic operation, infertility, ectopic pregnancy or spontaneous abortion and had less actual pelvic inflammatory changes than the 259 patients without contraception (57%), the IUD seemed to be directly involved with the increased risk of ectopic pregnancy. In the present study lower abdominal pain occurred in 97% of the patients and menstrual disorders in 93%; pelvic examination revealed adnexal mass in 63% and adnexal tenderness in 90% of the patients. Laparoscopy, a sensitive urinary pregnancy test (detection limit 75 IU/1) and culdocentesis were the most important factors in the diagnosis of ectopic pregnancy as evidenced by positive results in 97, 90 and 83% of the cases, respectively. Due to improved diagnostic procedures the annual rate of an unruptured tube at operation increased from 49% to 73% during the study period.