OBJECTIVE To report the exceptional condition of retroperitoneal ectopic pregnancy after intrauterine insemination. METHODS Case report. METHODS University hospital. METHODS A 37-year-old woman, gravida 2, para 1, presented to the emergency department 1 month after intrauterine insemination complaining of lower abdominal pain. METHODS A transvaginal ultrasound assessment revealed a complex mass containing a gestational sac with vitelline vesicle behind the left ovary. At laparoscopy, a nodular lesion was seen next to the left uterosacral ligament, suggesting the presence of an ectopic pregnancy in the retroperitoneal space. METHODS The unusual location of an ectopic pregnancy such as in the retroperitoneum should be examined in patients with clinical findings that suggest ectopic pregnancy if both the uterus and adnexa are normal during laparoscopic exploration. RESULTS The patient's retroperitoneal pregnancy was treated with a wide laparoscopic excision. To allow the removal of all trophoblastic tissue, a 3×2×2 cm hemorrhagic mass containing the ectopic pregnancy was removed from the retroperitoneal space. Retroperitoneal ectopic pregnancy was confirmed by the pathology diagnosis. CONCLUSIONS Retroperitoneal pregnancy after assisted reproductive techniques is an exceptional condition that must be considered in patients with clinical findings that suggest ectopic pregnancy if both the uterus and adnexa are normal during laparoscopic exploration.