This ORBCoN course focuses on blood transfusion and the possible reactions after a transfusion. At the end of this course you will be able to define a group and screen, name the type of crossmatch required when an antibody screen is positive, list the indications for red blood cells, platelets, plasma and fibrinogen replacement, estimate the frequencies of transfusion reactions to blood components in Canada, recognize the signs and symptoms of an adverse reaction to blood and blood components, and summarize measures for the management and prevention of transfusion reactions.