Background: Multiparameter flow cytometry is the most important method for the lineage assignment and maturational analysis of acute leukemias (AL) cells. The multi parametric immunophenotyping analysis allows the detection of aberrant antigen expression and the analysis of heterogeneity and clonality of malignant cells in AL. The aim of the work is to study the immunophenotypes of blasts from patients with AL and determine the frequency of aberrant markers. Subjects and Methods: Retrospective study to analyze immunophenotypic data of de novo 144 AL patients who were diagnosed in Clinical Pathology Department, Sohag University. Results: We found that 61.8% of AL patients were classified as acute myeloblastic leukemia (AML) while 38.9% classified as acute lymphoblastic leukemia (ALL). The commonest FAB subtype in AML group was AML-M2 (31.8%) followed by M4-M5 27.3%. As regard ALL, there were 85.7% with B-ALL and 14.3% with T-ALL. The aberrancy expressions were found in 66 of AL cases (45.8%), CD7 was the most commonly expressed lymphoid antigen in AML (25%), CD13 was the most commonly expressed myeloid antigen in ALL (39.3%). Conclusion: The multi parametric immunophenotyping analysis of AL is sufficient for diagnosis and classification of leukemia. The frequencies of aberra