Platelet transfusions are beneficial to treat or prevent bleeding in the thrombocytopenic patient. They are frequently used in patients with hypoplastic bone marrow, in cardiovascular surgery patients, and those involved in trauma. Because platelets have short survival, large numbers of platelet units are required. Also, platelet transfusions are expensive and not without complications. They can cause alloimmunization, provoke transfusion reactions, or transmit infectious disease, of which hepatitis C (non-A, non-B hepatitis) is of greatest concern. Therefore, documented indications and close monitoring of the transfused platelets are necessary.