Juvenile granulosa cell tumors of the ovary (JGCTs) are a rare form of neoplasm that makes up less than 5% of ovarians tumors in childhood and adolescence. About 90% are diagnosed in stage I (FIGO) with a favorable prognosis, whereas those at higher stages have a less favorable outecome. The authors describe a juvenile granulosa cell tumor expressed by an early pseudopuberty occurring in a 6 year old child. Clinically, an endocrine syndrome was associated with a pelvic mass. Hyperoestrogenia and serum alphafoetoprotein level were biologically detected. Tumor was localized strictly to the ovary, so conservative surgery was applied and proved sufficient to remove all tumor tissue. Histological examination showed typical microscopic aspect of a juvenile granulosa cell tumor. The patient is well, 14 years after surgery with a normal growth and mental developpment.