Thirty-eight patients with primary resistant or relapsing acute myeloid leukemia (AML) were treated with fludarabine, cytarabine and granulocyte colony-stimulating factor (FLAG). Median age was 41 (range 11-70). Sixteen patients had AML that was primary resistant to induction treatment, while 22 were relapsed, 11 after autologous bone marrow transplant (AuBMT), 8 less than 6 months from complete remission (CR) achievement, and 3 were second relapse from chemotherapy alone. Overall, 21 of 38 patients (55%) obtained CR. Age, sex, length of CR, and interval between autoBMT and FLAG administration did not significantly influence the CR rate. On the contrary, a normal karyotype at diagnosis was significantly related to a better outcome. There were 4 induction deaths (10%), due to fungal infection in 2 patients and hemorrhagic complications in the remaining two. All patients experienced profound cytopenia. Median time to neutrophil (>500/microl) recovery was 21 days, while a platelet count >20,000/microl was reached after 23 days. The median period of hospitalization was 31 days. The nonhematological toxicity was mild, mainly consisting of mucositis. There were 17 documented infections and 17 episodes of fever of unknown origin. Following CR achievement, 6 patients received autoBMT, 3 alloBMT, 2 high-dose arabinosil-cytosine, and 2 are on a waiting list for transplantation procedure. We conclude that FLAG is an effective and well-tolerated regimen for refractory or recurrent AML, mainly useful for patients to be admitted to bone marrow transplantation.