Seventeen cases of heterotopic pregnancies are reported among 1648 clinical pregnancies after in vitro fertilization. The high prevalence of tubal damage among IVF patients and the use of superovulation and multiple embryo transfer might predispose patients to the condition. Nine patients reported abdominal pain and vaginal bleeding, five patients did not have symptoms, and three had acute abdominal emergencies. Transvaginal ultrasonography was superior to transabdominal ultrasonography in the diagnosis of extrauterine pregnancies. The presence of an intrauterine gestation sac in a patient without symptoms should not exclude the diagnosis of a concomitant extrauterine pregnancy until the pelvis is carefully visualized. Early diagnoses of viable ectopic pregnancies before rupture abolishes mortality and morbidity and offers the chance of patient selection for conservative treatment. In two patients the extrauterine gestation sac was treated by transvaginal aspiration and injection of potassium chloride under ultrasonographic guidance. The outcome of the intrauterine pregnancy was favorable regardless of the method of treatment of the ectopic pregnancy.