We evaluated efficacy and toxicity profiles of fludarabine, Ara-C, idarubicin, and G-CSF (Ida-FLAG) combination chemotherapy in 56 refractory and/or relapsed acute leukemia patients. Patients were treated with fludarabine phosphate 25 mg/m2/d (d1-5), Ara-C 2 g/m2/d (d1-5), idarubicin 12 mg/m2/d (d1-3), G-CSF was given subcutaneously from sixth day until absolute neutrophil count (ANC) >500/microL. One third of the acute myeloblastic leukemia (AML) and 45% of acute lymphoblastic leukemia (ALL) cases were primary refractory disease. In AML patients, complete remission (CR) was achieved in 15 cases (53.6%). One case showed partial remission (PR) (3.6%) and 12 cases (42.8%) had resistant to this regimen (RD). Grade IV hematologic toxicity occurred in all AML cases. Leukocyte recovery time was 16 days. Nonhematologic complications were mild to moderate nausea, vomiting, and mucositis and could be controlled by routine measures. Stem cell transplantation was performed in 5 patients and all achieved CR, 2 autologous and 3 allogeneic. In ALL patients, CR and PR were obtained in 8 (42.2%) and 2 (10.5%) of 22 cases; disease was resistant to Ida-FLAG in 9 (47.3%) cases. Grade IV hematologic toxicity occurred in all ALL cases. Leukocyte recovery time was 17 days. Nonhematologic toxicity consisted of nausea, vomiting, and mucositis and could be controlled by supportive therapy. Autologous transplantation was performed in 1 patient, but relapse disease occurred after 5 weeks. There was no correlation between response rate and leukemia subtype (AML versus ALL), leukocyte count, age, sex, disease status (de novo versus secondary), and RFS (early versus late relapse) (P > 0.05). Median survival was 16 weeks in all cases (22 weeks in AML versus 13 weeks). At present, only 3 patients are alive and 2 of these are in continuous remission. The rest of the patients died. In conclusion, Ida-FLAG is a good choice in cases with refractory/relapsing acute leukemia for salvage chemotherapy. High efficacy and a low-toxicity profile are preferable properties of this regimen, and this regimen has been found to be useful for cytoreduction, especially in candidates for allo-SCT.