Fludarabine, cytarabine, granulocyte colony-stimulating factor (G-CSF), and idarubicin (FLAG-IDA) regimen has been proven to be a potentially useful chemotherapy regimen for relapsed or poor-prognosis childhood leukemia. The aim of the study was to evaluate complete remission (CR) rate, toxicity, and overall survival of children with poor-prognosis acute leukemia who received the FLAG-IDA regimen. Furthermore, the authors investigated the children who achieved CR following FLAG-IDA treatment regarding their eligibility for allogeneic hematopoietic stem cell transplantation (HSCT). Between January 2002 and April 2007, 25 children with poor-prognosis acute leukemia were treated with FLAG-IDA regimen in our center. Of the 25 children (16 AML, 9 ALL) with poor-prognosis acute leukemia, 7 (28.0%) received 1 cycle, 17 (68.0%) received 2 cycles, and 1 (4%) received 3 cycles of FLAG or FLAG-IDA regimen. After 44 cycles of FLAG-IDA or FLAG regimen, 10/25 (40%) children were nonresponders, 15/25 (60.0%) showed CR. Five (20%) of these patients in CR who underwent allogeneic HSCT are still in remission. The remaining 20 (80.0%) children were lost due to infection or relapse of the primary diseases. The overall survival of patients who are still alive and underwent allogeneic HSCT (mean: 40.6 +/- 4.7, median: 40, range: 34-46 months) was longer than that of patients (mean: 5.5 +/- 4.3, median: 4, range: 1-15 months) who did not undergo allogeneic HSCT. The CR rate was quite high in the present study using the FLAG-IDA regimen, and the authors believe this regimen is a possible option prior to allogeneic HSCT in children with poor-prognosis acute leukemia.