BACKGROUND: Combination treatment with all-trans-retinoic acid (ATRA) and anthracycline-based chemotherapy has led to major advances in the treatment of acute promyelocytic leukemia (APL). METHODS: In this study, we reviewed the outcome of pediatric APL patients treated using a modified AIDA protocol at our institution. RESULTS: Between May 1999 and December 2007, 23 patients were diagnosed with APL at the Department of Pediatrics, Saint Mary's Hospital, The Catholic University of Korea. Eleven patients were male (48%) (median age at diagnosis, 11 (range, 2-14) years). The treatment protocol consisted of remission induction (achieved by coadministration of ATRA and idarubicin), 3 courses of consolidation treatment, and 2 years of maintenance treatment during which ATRA was also administered. Three patients died early during remission induction due to CNS hemorrhage. The remaining 20 patients achieved complete remission (CR), with an overall CR rate of 87%. Two patients relapsed and died, and another patient died of pneumonia unrelated to APL. Four patients (17%) were diagnosed with ATRA syndrome, and all patients showed resolution of symptoms. The event-free survival (EFS) and overall survival (OS) of the cohort were 78.3+/-8.6% and 76.3+/-9.5%, respectively. Initial WBC count at diagnosis was the only significant prognostic factor for the rate of CR (P=0.039) and OS (P=0.039). CONCLUSION: A modified AIDA protocol for the treatment of childhood APL leads to improved EFS and OS, with limited ATRA syndrome-associated toxicity. Active monitoring and treatment of patients with high initial WBC counts may help in reducing mortality.