Complex karyotype (CK) typically involves various, often extensive numerical and structural chromosomal abnormalities. In chronic lymphocytic leukemia (CLL), it represents an established biomarker of adverse outcome. Common methods to detect CK include classical cytogenetics and genomic microarray; additional information may be obtained using next generation sequencing (NGS). However, all these approaches show low accuracy and sensitivity for detecting complex structural variants at the DNA sequence level. We aimed to explore the ability of long-read sequencing for the precise characterization of complex genomic variants in CLL patient samples.