Leiomyomas are benign smooth muscle tumors which can be uterine or extrauterine. Extrauterine leiomyomas are uncommon. In this article, we report a case of large retroperitoneal fibroid in 26 year old female who presented with sudden onset of severe right iliac fossa pain. Her medical, surgical and gynaecological history was insignificant. Provisional diagnosis, based on investigations, was ovarian mass. Intra operatively huge pelvic retroperitoneal mass was observed. Pathological examination demonstrated benign leiomyoma.