Ovarian sex cord tumors are rare tumors that develop at the expense of non-germ cell ovarian. The pathogenesis of these tumors remains undetermined and several cellular and molecular alterations may be involved in the development of juvenile granulosa cell tumors. For two decades, the individualization of juvenile granulosa cell tumors has been a major advance in the treatment of these children's tumors. However, their natural history is reported in the literature and through a short series and reliable prognostic factors are to establish. We report the case of a girl of 8 years who presented with abdominal-pelvic mass gradually increasing size, to surgical exploration found a huge abdominal mass at the expense of the left ovary. Histology and objective immunolabeling a tumor of the juvenile form of granulosa.