Complex karyotype (CK) predicts poor prognosis in chronic lymphocytic leukemia (CLL). CK detection is routinely assessed by chromosome banding analysis (CBA) or chromosomal microarrays (CMA), although results obtained by both techniques are not equivalent. In this setting, our group has assessed 42 CLL patients by optical genome mapping (OGM) with the aim to analyze the utility of this a novel technology in the cytogenetic assessment of CLL patients. Besides the global concordance of OGM with current techniques, the talk will be focused in some examples of the new information from previously known abnormalities underscored by OGM.