The following report describes the case of an ectopic pregnancy with contralateral corpus luteum after spontaneous conception. The patient was a 33- year-old female (gravida 3, segmentary C sections 3), with positive pregnancy test, and an Intrauterine Device (IUD). The patient was asymptomatic. At vaginal ultrasound, we observed an anteverted uterus of normal shape and size, a 20 x 12 mm intramural myoma and an irregular endometrial thickness of 16.5 mm, with no intrauterine sac. An ectopic pregnancy in the left Fallopian tube and a contralateral corpus luteum were detected, possibly as consequence of ovum pick up through the opposite tube (oocyte transmigration). Further laparoscopic and histopathologic studies confirmed our findings, and the ectopic pregnancy was successfully removed. In conclusion, oocyte transmigration is a common event and should be account when we wish to provide medical advice to patients with a single Fallopian tube trying to conceive. There are real chances for a patient to become pregnant even when only a single tube is present.