This booklet provides information about blood transfusion for patients with leukemia, lymphoma and myeloma (blood-related cancers) and their families. We welcome your comments on the clarity of the presentation and additional topics that should be included in the future. Each year about 12 million units of blood are collected from healthy volunteers and 3 million patients are transfused with blood components. On average each unit is made into three different components, red cells, platelets and plasma. Most of the red cells are transfused to patients undergoing surgical procedures. However, patients with blood-related cancers frequently receive platelets and some red blood cells. They may require more blood components overall than surgical patients because their need is likely to be prolonged over a number of weeks. In addition, most patients who undergo marrow or blood stem cell transplantation will be transfused. The most frequently asked questions about blood transfusion relate to the safety of the blood supply, diseases that can be transmitted by blood components, other complications that may occur following blood transfusion and what is being done to reduce those risks. These topics will be covered.