Chronic lymphocytic leukemia is a disease of older individual it is characterized by clonal proliferation of mature CD5+ CD19+ CD23+ B lymphocytes and weak surface expression of monoclonal immunoglobulin B cell receptor. CLL cells accumulate in the peripheral blood, bone marrow, lymph nodes and spleen. CD38 is a transmembrane glycoprotein that is normally expressed at high levels in B cell precursors, germinal center B cells, and plasma cells, with low expression on circulating B cells in CLL. The aim of this study is to evaluate the pattern of the prognostic marker of CLL (CD38) in Sudanese patients with correlation with the score. This is descriptive cross sectional study in which 43 peripheral blood and bone marrow samples from patients with chronic lymphocytic leukemia were incubated with anti human CD38 and analyzed using flow cytometer. (74.4%) of the study population were male and (25.6%) were female. We found that (93%) of patients were positive CD38 and (7%) were negative. We found that the flow cytometric parameters of CD38 expression showed significant importance in CLL cases score and there was significant relation with CD38 and CBC finding (TWBCs,RBCs and platelets count). Sample size may help in the understanding of these relations especially if correlate with prognosis outcome of the treatment. We found that the relations of CD38 flowcytometric parameters (Percentage and peak width) were significant in the differentiation between variable score of CLL Sudanese patients. The expression of CD38 is highly associated with female more than males and its level elevated with the drops of WBCs, RBCs and platelets. We recommended that making more studies in the same population with correlation with more prognostic markers by cohort study