Aim: Sperm cryopreservation (SCP) should be offered to every adolescent before gonadotoxic treatment, but experience in this age range is still relatively limited. The goal of this study is to assess how to optimize this procedure. Methods and Patients: One hundred thirty-three patients between 12 and 20 years old, who underwent SCP between 1980 and 2017, were included. Baseline data (age, indication for SCP, and semen parameters at freezing) and follow-up data (outcome of sperm straws and follow-up of sperm quality) were collected and analyzed. Results: SCP is feasible from the age of 12. Semen assessment parameters at this age were close to parameters of adults. However, we observed quantitative impairments in testicular tumors and qualitative impairments in leukemia and bone marrow failure. Four patients (3%) used their cryopreserved semen for medically assisted reproduction, 15 patients died (11.3%), 18 asked for destruction of their straws (13.5%), and nine samples were destroyed because of lack of news (6.8%). Very few patients underwent a sperm analysis after treatment. Conclusions: SCP is an efficient, still underused, procedure for adolescents and young adults. Cryopreserved sperm is rarely used and rarely destroyed, but studies with a longer follow-up are needed to better assess these observations. Follow-up with a specialist of reproductive medicine is valuable for better information of the patient.