The "Atlas of Clinical Hematology" in its 6th edition offers a comprehensive and detailed presentation of clinical hematology. This edition integrates the WHO classification from 2001 and documents newly described types of leukemias and lymphomas, including rare forms and specific diseases such as persistent polyclonal B-lymphocytosis. The atlas covers all microscopic methods relevant for diagnosis in hematology and takes into account the results of modern immunological, cytogenetic, and molecular genetic investigations. Special attention is given to the cytogenetic and molecular genetic characterization of biological entities that could serve as a basis for innovative therapies. The atlas provides a valuable reference framework that is essential for online diagnostics and scientific research in hematological and oncological departments as well as clinical laboratories.