Cryoprecipitate is prepared from fresh frozen plasma; it is the material that does not become totally liquid when fresh frozen plasma is slowly thawed and the major part has liquefied. Cryoprecipitate contains about 50% of the original factor VIII and von Willebrand factor activity, about 20%-40% of the fibrinogen and some factor XIII. The major advantage over fresh frozen plasma is reduction in the total volume of fluid that is transfused. Transfusion of one unit of cryoprecipitate carries about the same risk of hepatitis or HIV-I infection as transfusion of one unit of fresh frozen plasma or one unit of whole blood. Cryoprecipitate can also transmit infection by cytomegalovirus and Epstein-Barr virus. The amount of factor VIII activity in each unit of cryoprecipitate is reported to be highly variable (from approximately 25-150 units), although each bag is supposed to contain at least 80 units. Each unit contains about 150 mg of fibrinogen. Cryoprecipitate is useful in treating von Willebrand’s disease as well as hemophilia A. Some reports suggest that cryoprecipitate, for unknown reasons, has some corrective activity in uremic patients with a bleeding tendency. If many units of cryoprecipitate are administered, some believe that ABO-compatible units should be used, since cryoprecipitate is a plasma preparation and could contain anti-A and anti-B antibodies. These antibodies could produce a positive direct Coombs’ test result on recipient RBC, which would be confusing. However, the need for ABO compatibility has been disputed. Large amounts of cryoprecipitate might elevate plasma fibrinogen levels and through this mechanism could produce a temporary elevation of the RBC sedimentation rate.