Fetal ovarian cysts are the third cause of intra-abdominal cyst after renal and gastrointestinal cyst. The presence of these cysts can be suspected on ultrasound examination when a mass with a regular cystic structure is found in the inferior lateral region of the abdomen of a female fetus without urinary or intestinal tract anomalies. We report the case of an 18-year-old primigravida in whom ultrasound examination revealed an apparently soft tumor in the inferior, right region of the abdomen, corresponding to a fetal ovarian cyst clearly identified and separated from the bladder. A female newborn was delivered by cesarean section and was discharged on the third day of life without complications. At 3 months, spontaneous disappearance of the cyst was observed.