The diagnosis of leukaemias and lymphomas is undergoing continuous change. Besides new molecular markers such as NPM1 or JAK2 that have become important diagnostic and prognostic parameters, special laboratory methods have also continued to develop apace and the diagnostic relevance of these has rapidly increased. For the sake of our patients, a comprehensive diagnosis, the best possible targeted therapy and lastly the best possible prognosis, the available methods need to be used in a targeted and cost-effective manner. This textbook is a rapid aid and guide in everyday professional activity for oncologists, healthcare workers and medical laboratory personell dealing with the diagnosis of leukaemias and lymphomas.