A phase II trial was designed to explore the potential feasibility and efficacy of a reinduction therapy consisting of fludarabine, cytarabine, idarubicin and granulocyte colony stimulating factor (G-CSF) for acute myelogenous leukaemia (AML) patients with poor prognosis. Twenty-three patients aged 1 2-17.5 years with refractory (n=3), relapsed (n=19) or secondary (n=11) AML were treated with the IDA-FLAG regimen, a combination therapy of idarubicin (days 2-4, 12 mg/m2/d), fludarabine (days 1-4, 30 mg/m2/d), cytarabine (days 1-4, 2000mg/ m2/d) and G-CSF (day 0 up to ANC > 1 x 10(9)/l, 400 microg/m2/ d). They received a total of 3 7 courses of IDA-FLAG and/or FLAG (IDA-FLAG without idarubicin). 17/23 patients achieved a complete remission (CR) with a median duration of 13.5 months (1-39 months), one patient showed a partial remission, and five were nonresponders while in CR, 11 patients underwent bone marrow or PBSC (peripheral blood stem cells) transplantation. Overall, nine patients remain in continuous complete remission with a median duration of 17.5 months (9.5-39 months). The toxicity of the IDA-FLAG courses was more severe than for the FLAG courses with marked neutropenia and thrombocytopenia (for IDA-FLAG: median 22.5 and 25 d respectively; for FLAG: median 10.5 and 14 d respectively). Pulmonary infections were the main nonhaematological toxicity. One patient died in CR from invasive aspergillosis. The IDA-FLAG regimen produced a CR of >12 months in more than half of the patients and can be recommended as a therapeutic option prior to allogeneic or autologous bone marrow transplantation.