We conducted a multicenter postmarketing study to investigate the efficacy and safety of reinduction therapy with a high-dose cytarabine-containing regimen for pediatric patients with relapsed or refractory acute leukemia. Seven of 13 patients (53.8%) with ALL achieved complete or partial remission, and only 1 of 6 patients (16.7%) with AML achieved partial remission. The frequent non-hematologic adverse events were gastrointestinal toxicities, such as vomiting, diarrhea and abdominal pain, as well as pyrexia and headache. Infection appeared in 9 of 20 (45%) patients. There were two death during reinduction therapy. One died of invasive bronchopulmonary aspergillosis, and the other died of intracranial hemorrhage and renal failure. These results indicated that a high-dose cytarabine regimen is effective as reinduction therapy in pediatric patients with relapsed ALL, and supportive care is essential to prevent or control treatment-related adverse events, such as infection.