Chronic lymphocytic leukemia (CLL) is a monoclonal malignancy characterized by an accumulation of small and mature looking B lymphocytes in the blood, bone marrow and other tissues. The Blymphocytes developed in a wrong way lead to an immune disorder, and are typically characterized by expression of some of CD markers as (CD5,CD38 and ZAP-70) determined by immunophenotyping. The aim of this study was to investigate the extent to which immunological, biochemical, and molecular parameters are altered in CLL patients, and the potential of applying these alterations as biomarkers for CLL in Iraqi patients. the present study included 64 patients of CLL and 48 healthy individuals were investigated for Notch homolog 1, translocation-associated (Drosophila) (NOTCH1) c.7544-7545delCT, The presence of NOTCH1 mutations were confirmed by genomic DNA sequencing. The NOTCH1 mutation was detected in 15% of patients and not detected in the control group. The current study established the frequency of NOTCH1 mutations in patients with CLL from the iraqi population of the National Center of Hematology AL-Mustansiriyah University and Hematology Department of Baghdad Medical City. In summary, a high frequency of NOTCH1 and SF3B1 mutations were identified in patients with CLL compared with healthy individuals, and the NOTCH1 mutation was found in 15% of CLL patients The alignment results of the 341 bp samples revealed the presence of only one genetic variation variably distributed in some of the analyzed samples patients in comparison with the referring NOTCH1 genetic sequences , The identified variations were only found to be confined with the targeted rs763016003 frameshift variant. In a total of eleven investigated samples, S2, S3, S5, and S7 were placed as control, while the rest of the samples (S15, S19, S20, S31, S41, S49, and S51) belonged to patients. The targeted rs763016003 frameshift variant was not found in all involved control samples. Meanwhile, this rs763016003 variant was found in most of the patient samples (S15, S19, S31, S41, S49, and S51).