This chapter describes the anaesthetic management of the patient with a haematological disorder. Topics covered include anaemia, sickle-cell disease, porphyria, coagulation disorders, haemophilia and related disorders, platelet disorders, and hypercoagulability syndromes. For each topic, preoperative investigation and optimization, treatment, and anaesthetic management are described. There is detailed discussion about the perioperative management of the patient taking a drug which affects the coagulation system, including anticoagulants, antiplatelet drugs, and fibrinolytic and antifibrinolytic drugs. Coagulation tests are discussed in detail, and the haematological management of the bleeding patient is described.