Abstract： Objective To study the relationship of immunophenotype and prognosis of acute leukemia(AL). Methods 75 patients with AL were analyzed immunophenotype expression by FCM and evaluated the effect of differ-ent immunophenotype to prognosis. Results (1) The incidence of CD13, CD33, CD64, CD117 expression in AML was 82%. The incidence of CD2, CD3, CD7, CD19, CD20 expression in ALL was 88%. The incidence of lymphocytic lineage antigen expression in AML(Ly + AML) was 13% and myeloid lineage antigen expression in ALL(My + ALL) was 11%. (2)According to the antigen expression, AL could be classified into three subgroups:lineage-specific expres-sion;mixture-lineage expression and null type. The lineage-specific expression was the highest in AML and ALL, and had a better clinical prognosis. The null type was the lowest neither in AML nor ALL and had a poorer clinical progno-sis. In mixture-lineage expression the CR rate of AML with CD7+ was the lowest than those with lineage-specific ex-pression and had poorer prognosis. Conclusions AL immtmophenotype might be devided into three subgroups:line-age-specific expression; mixture-lineage expression and null type. In the patients with CD7+ AML and null type ex-pression,lower CR rate and poorer prognosis were seen than those with lineage-specific expression. It needed to ex-plore new treatment methods.