CLL with 17p deletion and TP53 mutation show an increased but differential degree of genetic complexity. The analysis of the number of chromosomal gains or losses showed a significant increase of the number of cytogenetic aberrations in the cases with 17p deletion (mean ± SD, 3.75 ± 1.65) and TP53 mutations (no 17p deletion, 2.4 ± 1.3) versus cases without either abnormality (0.9 ± 0.8; P < .001 and P = .0005, respectively). CLL cases with 17p deletion showed a higher complexity compared with cases with the mutation of TP53 only (P = .03).