Introduction: The incidence of extrauterine pregnancy increases to 2–12% following in vitro fertilization–embryo transfer. Several pathogenic theories have been suggested, including abnormal hormonal secretion or exogenous hormones administered in assisted reproductive technology (ART). Case report: A 32-year-old nulliparous woman with primary infertility and Stage 3 endometriosis was treated by ART with intracytoplasmic sperm injection and embryo transfer. The patient showed simultaneous bilateral extrauterine pregnancy, managed by laparoscopic salpingectomy. Discussion: The various possible pathophysiological mechanisms are described, with a review of the literature on simultaneous bilateral extrauterine pregnancy following ART. In pregnancies following ART, ectopic pregnancy should always be screened for by serum β-human chorionic gonadotropin monitoring and transvaginal ultrasound until the implantation site can be confirmed as the incidence is higher than in spontaneous pregnancy. Even if serum β-human chorionic gonadotropin concentration increases normally, possible bilateral ectopic pregnancy should always be investigated if no intrauterine gestational sac can be seen. Keywords: bilateral ectopic pregnancy, embryo transfer, endometriosis, in vitro fertilization, intracytoplasmic sperm injection