The objective of this study was to evaluate the efficacy and toxicity of the fludarabine combination with high-dose cytarabine (Ara C), idarubicin and granulocyte colony-stimulating factor (G-CSF) (IDA-FLAG regimen) in treatment of refractory/relapsed acute leukemia (AL) patients. 4 patients were male aged from 32 to 44 years, consisted of 3 cases of acute myeloid leukaemia (AML) and 1 cases of acute lymphocytic leukaemia (ALL). All the patients were treated with idarubicin (10 - 12 mg/m(2)/d, days 1 to 3), fludarabine (50 mg/d, days 1 to 5), cytarabine (2 g/m(2)/d, days 1 to 5) and granulocyte colony-stimulating factor (G-CSF, 300 microg/d, days 0 to 5). The results showed that after one course of induction therapy, 4 patients all achieved complete remission (CR), in which 2 patients were in continuous CR after a follow-up of 3 and 4 months; 1 patient relapsed after 10 months and another one patient died of thrombotic thrombocytopenic purpura at 4 months after allogeneic peripheral blood stem cell transplantation. Myelosuppression and infections due to neutropenia were the most frequent adverse effects, severe nonhematologic toxicity and the early death were not observed in these patients. In conclusion, the IDA-FLAG regimen is effective in treatment of patients with refractory and relapsed AL, the adverse effects from this regimen were well tolerated by patients, which gains time for further treatment.