We report the case of a patient with unicornuate uterus and an intrarudimentary horn first-trimester ectopic pregnancy. This rare pregnancy was diagnosed by laparoscopy and did not respond to systemic methotrexate treatment. The clinical presenting symptoms and signs were similar to those of an extrauterine pregnancy. Following the failure of methotrexate treatment, a second operative laparoscopy was performed, and definitive treatment was obtained by resection of the rudimentary horn containing the pregnancy. Debates about and rationale for the elected treatment are described.