Epidermoid cyst is a frequent benign cutaneous tumor. The pelvic localization does not occur very often. The literature that taps into such cases is very limited in scope. Here is a report of a 27-year-old woman with a giant pelvic retroperitoneal epidermoid cyst. The use of ultrasound exploration and computed tomography has indicated ovarian origins. The surgery also revealed a retroperitoneal epidermoid cyst, uterus and ovaries were all intact. The evacuation of a cyst was found to contain lamellas of keratin. Histology permitted us to confirm the diagnosis. The patient was faring well after two years of followup.