Chronic lymphocytic leukemia (CLL) is a B-cell lymphoproliferative disorder. The diagnosis of CLL requires the presence of 5x109/L lymphocytes in the peripheral blood and infiltration of bone marrow more than 30% of lymphocytes and also expression of CD5, CD20, CD19 and CD23 antigenes. This disorder usually affects people of older age and the incidence of CLL increases with age and it is twice as common in men. There are three staging system: Rai, Binet, and Total tumor mass score. CLL can be asymptomatic or may have a wide range of symptoms. It may include lymphadenopathy, splenomegaly, hepatomegaly and nonspecific symptoms like extreme fatigue, paleness and unintentional weight loss. The diagnostic procedure includes a medical history and physical examination, blood tests, morphologic analysis of bone marrow, immunophenotyping search and cytogenetic search. Unfavorable prognostic factors are: elderly age, male sex, high clinical staging (Rai 3 and 4, Binet C), gene mutations in TP53, high level of beta-2 microglobulin, LDH, expression of CD38 equal or higher than 30%, and expression of ZAP-70 equal or higher than 20%. CLL is an incurable disorder but therapy can prolong life and decrease symptoms Only one third of newly diagnosed patients should be treated immediately. First-and second-line treatments are available. The “gold standard“ is FCR chemotherapy. It may also involve Ibrutinib, Idelalisb, and Chlorambucil. Monoclonal antibodies are increasingly used for therapeutic purposes as well. Second-line treatment with kinase inhibitors such as Ibrutinib, Idelalisb, and Venetoklast is the choice for patients with a relapse. Also, one of the options is allogeneic stem cell transplantation. CLL is an indolent hematological neoplasm and five-year survival rate is expected in more than 69% patients. The five-year survival rate is shorter when a patient has unfavorable prognostic factors, especially genetic mutations in TP53.