In paediatric female patients the only option for restoring fertility after chemotherapy and radiotherapy is ovarian tissue banking. Even if this procedure is considered the most promising available, anyway it is still an experimental option due to the paucity of data. The possibility to offer an experimental preventive technique with potential benefits but with known risks arises a dilemma: what is the best interest for suffering child? Is it most important to minimize risk of the disease or to preserve the future fertility? However, if it is right to propose fertility preservation when physical and psychic risks are acceptable, we think it is not in the child's best interest to retrieve ovarian tissue from very young patients whose ovaries are small and for whom surgery is a high risk procedure. Moreover fertility preservation should not be offered if this could increase the risk of disease worsening.