CD20 and CD19 are cell surface protein and are considered important in the differentiation of chronic lymphocytic leukemia (CLL) from other lymphoid leukemias. MFI of CD 20 is a simple, accurate parameter in differentiation between CLL and low grade non Hodgkin lymphoma. We studied fifteen B –CLL patients, ten leukemic phase of NHL patients, ten low grade NHL patients and ten normal volunteers as a control group. We found both CD20 and CD19 were highly significantly elevated in CLL patients as compared to the normal control group (p value < 0.01). We found that MFI of CD20 was statistically elevated in CLL patients as compared to the normal control group.