The fifth edition of "Catalog of Chromosome Aberrations in Cancer," edited by Felix Mitelman, is a comprehensive reference book on aberrant karyotypes in malignancy. It includes data from over 22,000 individual neoplasms, drawn from 5,224 references, reflecting the rapid growth in this field of research. The book is divided into two volumes, covering chromosomes 1–12 and 13–22XY. Cases are classified by chromosome, and a single case may appear under multiple chromosomes. Solid tumour entries account for 27% of cases, compared to 12% in 1983. The edition uses the International System for Cytogenetic Nomenclature 1991 and includes updated information on karyotypes investigated by molecular techniques. Entries are subclassified by disease types, including 46 haematological disorders, 35 malignant lymphomas, and 98 solid tumours. Cases are sourced from over 30 scientific journals worldwide, with Europe being the largest contributing continent and the UK the fourth largest contributing country. The book highlights the diversity of chromosomal aberrations in cancer and their role in initiating mutagenesis. It serves as a valuable resource for researchers working on cytogenetic or molecular changes in malignancy, providing a comprehensive bibliography for accessing published cases. The fifth edition is well-designed, user-friendly, and essential for researchers seeking up-to-date information on chromosomal abnormalities in cancer.The fifth edition of "Catalog of Chromosome Aberrations in Cancer," edited by Felix Mitelman, is a comprehensive reference book on aberrant karyotypes in malignancy. It includes data from over 22,000 individual neoplasms, drawn from 5,224 references, reflecting the rapid growth in this field of research. The book is divided into two volumes, covering chromosomes 1–12 and 13–22XY. Cases are classified by chromosome, and a single case may appear under multiple chromosomes. Solid tumour entries account for 27% of cases, compared to 12% in 1983. The edition uses the International System for Cytogenetic Nomenclature 1991 and includes updated information on karyotypes investigated by molecular techniques. Entries are subclassified by disease types, including 46 haematological disorders, 35 malignant lymphomas, and 98 solid tumours. Cases are sourced from over 30 scientific journals worldwide, with Europe being the largest contributing continent and the UK the fourth largest contributing country. The book highlights the diversity of chromosomal aberrations in cancer and their role in initiating mutagenesis. It serves as a valuable resource for researchers working on cytogenetic or molecular changes in malignancy, providing a comprehensive bibliography for accessing published cases. The fifth edition is well-designed, user-friendly, and essential for researchers seeking up-to-date information on chromosomal abnormalities in cancer.