The aim of this study was to assess the prevalence of de novo malignancy after solid organ transplantation in childhood. A retrospective questionnaire-based survey was sent to 9 referral centers for pediatric organ transplantation in France. Among 1326 children who underwent solid organ transplantation since 1996, 80 (6%) presented with de novo malignancy posttransplantation during childhood: posttransplant lymphoproliferative disease was the most common (5% of pediatric recipients) comprising 80% of all tumors, with a disproportionately high prevalence among combined liver and small bowel recipients (18%). Various solid tumors were observed mainly among kidney recipients. No skin cancer was reported.