Objective: To explore the expressions of IL-10 on leukemic cells in acute leukemia patients and its significance.Methods: The expressions of IL-10 on leukemic cells in thirty patients was measured by indirect immunofluorescence technique. Results:Observed yellow-green bright fluorescence on leukemic cells membrane, the positive rate of cells was 10-80％, there were 18 patients expressing IL-10 (18/30, 60％) positively, among them 11 with ANLL (11/19, 58％) and 7 with ALL (7/11, 64％) respectively while that of peripheral mononucleate cells in control group was 13 ％. Compared with that in the control group, there was a significant increase of positive rate in ANLL and ALL but with no significant difference between ANLL and ALL. Conclusion: IL-10 secreted by leukemic cells, contributed to the immunosuppressive state at the tumor site. This is probably one of the important mechanisms of acute leukemic escape.