Objective To investigate the treatment of recombinant human interleukin-11(rhIL-11)to chemotherapy-induced thrombocytopenia in acute leukemia(AL).Methods 42 AL patients whose platelet count dropped below 20×109/L after chemotherapy received rhIL-11 by 1.5 mg daily until the platelet count was increased above 40×109/L.The efficiency of chemotherapy to 17 newly diagnosed acute myelocytic leukemia(AML)patients was evaluated after receiving two periods of chemotherapy.35 AL patients and 15 newly diagnosed AML patients were used as controls.Results The mean time of platelet count increasing from 20×109/L to above 40×109/L Was shorter in treating group (9.8±2.7)d than in control group(14.6±4.8)d .The number of patients whose platelet＜15×109/L was less in treating group than in control group after second chemotherapy,and the minimum mean count of platelet Was higher in treating group(23.5±18.3)×109/L than that in control group(10.2±9.8)×109/L .CR and CR+PR rate were not different between treating group and control group. Conclusion rhlL-11 can safely and effectively promote chemotherapy-induced platelet recovery in patients of acute leukemia with persistent affection.