For prepubertal patients, cryopreservation of ovarian tissue is the only option available to preserve their fertility before cancer treatment. But ovarian autograft raises the issue of the risk of reintroduction of potentially malignant cells. The aim of our study is to develop a specific and sensitive method for residual disease detection in the ovarian tissue from patients treated for a solid tumor during infancy, whose fertility may have been compromised by treatments and who benefited of ovarian tissue cryopreservation.