Blood transfusion is not without risk. Although the risks of HIV and hepatitis transmission have diminished, haemovigilance programs highlight that other significant transfusion hazards remain. Sepsis from bacterial contamination is the most common residual infectious hazard in developed countries, and events due to clerical error are problematic. Unnecessary transfusions should be avoided. New national guidelines on patient blood management (PBM) emphasise holistic approaches, including strategies to reduce transfusion requirements. Perioperative PBM should incorporate preoperative haemoglobin and medication optimisation, intraoperative blood conservation, and consideration of restrictive postoperative transfusion and cell-salvage techniques. When massive transfusion is required, hospitals should implement massive transfusion protocols. These protocols reduce mortality, improve communication and facilitate adequate provision of blood products. They should include multidisciplinary team involvement and guidelines for use of blood components and adjunctive agents. Although fresh frozen plasma to red blood cell and platelet to red blood cell ratios of ≥ 1 : 2 appear to reduce mortality in trauma patients who receive massive transfusion, there is insufficient evidence to recommend specific ratios. Systematic reviews have found no significant benefit of recombinant activated factor VII in critical bleeding, and an increase in thromboembolic events; specialist haematology advice is therefore recommended when considering use of this agent. The National Safety and Quality Health Service Standards address use of blood and blood products, and provide important transfusion principles for adoption by all clinicians. Storage of red cells in additive solution results in changes, known as the "storage lesion", and studies to determine the clinical effect of the age of blood at transfusion are ongoing.