Chromosome abnormalities arising leukemia cells by means of clonal evolution in nearly half of the surveyed patients with chronic lymphocytic leukemia are detected using cytogenetic analysis methods metafazalnych cells in vitro after stimulation with mitogens or cell type-molecular-FISH techniques or interfazalnych metafazalnych cells. The most common structural abnormalities in chronic lymphocytic leukemia B relate to partial deletion of chromosome 13 in the region 13q14 subcentromerowym, partial deletion of chromosome 11 in the region 11q23, trisomy chromosomu12 and mono-or biallelicznej loss of p53 tumor suppressor gene on chromosome 17p13. The significance of these markers for chromosome anomalies clonal B cell proliferation and / or progression of CLL-B.