Two cases of isosexual precocity in relation to granulosa cell tumor in 2 girls aged 6 and 9 months respectively are described. In the two cases clinical and biological signs of hyperoestrogenemia were found but in one, acute signs of tumoral rupture were the first symptom. Histologically, the two classical subtypes were found: macrofollicular ("adult" type) and "juvenile". These two children are alive without any sign of recurrence with a follow up of 12 and 18 months. The occurrence of granulosa cell tumors in such young girls seems extremely rare.