Rasburicase (Fasturtec), a recombinant urate oxidase, is highly effective in preventing and treating hyperuricemia in children with hematologic malignancies. We conducted a prospective, multicenter observational study in 174 patients at 8 pediatric hemato-oncology centers to establish whether the SFCE (Société Française de Lutte contre les Cancers et Leucémies de l'Enfant et de l'Adolescent) recommendations for the use of rasburicase in the management of pediatric patients at risk of tumor lysis syndrome (TLS) are valid in routine clinical practice. Patients were classified as being at high or low risk of TLS according to the Children's Oncology Group criteria and were treated in accordance with the SFCE recommendations. The primary end point was the number of patients requiring a higher dose of rasburicase or a longer duration of treatment than advised in the SFCE recommendations. Of the 135 patients at high risk of TLS, 27 patients received a higher dose and 35 patients received a longer duration of treatment. Some patients received treatment with rasburicase for less than the recommended duration (median 4 d for high-risk patients). One patient required hemodialysis. Only minor adjustments to the SFCE recommendations were required to ensure the optimal use of rasburicase in pediatric patients at risk of TLS.