The author's many years involvement in teaching, in examining and in the practice of laboratory haematology, together with frequent requests to recommend suitable books, have indicated a need for a single volume that combines physiology, pathophysiology and the practical aspects. The aim has been to produce a textbook that is more than adequate for first qualifications and a sound basis for further study, which will also serve as a bench-book in the haematology department of a general hospital. An attempt has been made to maintain a balance between the haematological disorders and the methods used in investigation, but in certain areas where technology is advancing rapidly, e.g. instrumentation or immunoassays using radioisotope or enzyme labels, we have confined the text to general principles and avoided recommending particular instruments and methods (or test kits!). This book is primarily for technologists, scientists and medical colleagues involved in laboratory haematology and although inevitably the content is related to laboratories and examinations in the United Kingdom, much of the content may be relevant to laboratory haematology in other countries.