Acute lymphocytic leukemia (ALL) is a neoplastic disease of immature lymphocytes or lymphocyte progenitor cells for either B-or T-cell lineage.The aim of our work is to evaluate the possible influence of Bcl-x on the genesis of acute lymphoblastic leukemia (ALL). Our study included 30 patient, 16 male and 13 female. There were 19 B-ALL cases, 8 T-ALL cases. One case was AML with aberrant expression of T-lymphoid markers, one case B-cell precursor ALL with aberrant expression of T-cell markers and one case of biphenotypic acute leukemia for both myeloid and T-lymphoid lineages.Out of 27 ALL cases, 16 cases were positive for Bcl-xL while 11 cases were Bcl-xL negative.None of the control group was positive for either Bcl-xL or Bcl-xS. No significant relation was found between the Bcl-xL positivity and the specific immunophenotypic markers. The three included bilineage cases were negative for both Bcl-xL and Bcl-xS. Concerning the outcome of the disease in relation to the Bcl-x, only three cases were relapsed and all of them were negative for Bcl-xL as well as Bcl-xS.