The Prepubertal Testicular Tumor Registry has been in existence for 12 years. Information on 327 patients was collected and registered in the database. Demographic data have been analyzed, leading to a better understanding of these rare tumors. Information regarding the natural history and behavior of the tumors has also evolved from a retrospective review of the tumors. The registry will continue in an effort to collect centrally information on these unusual tumors and to attempt to aid in developing a better understanding of the natural history and behavior of the tumors to provide early detection, consistent treatment and improved survival.