THE MECHANISM of action of intrauterine contraceptive devices (IUCDs) is still unknown. The reported tubal pregnancies in association with IUCDs make it evident that, in these cases, the device did not interfere with fertilization of the ovum in the fallopian tube. The purpose of this report is to record the first case of ovarian pregnancy, to our knowledge, in association with an IUCD. Report of a Case In June 1966, a 29-year-old, white, gravida 6 para 5 had a Lippes loop inserted. She did well until Jan 3, 1967, when her menses lasted for ten days. Bleeding began again on Jan 15 and persisted for ten days, and for eight more days beginning Jan 30. She continued to bleed almost daily until the time of her admission on Feb 23. Four weeks prior to admission, pain developed in the right lower quadrant of the abdomen, and continued until surgery. Examination