Severe allergic reactions to transfusion are sometimes found to be due to anti-IgA in recipients who are IgA deficient. Provision of adequate transfusion support for these patients is challenging, particularly if they require platelets and/or plasma. Novel methods have been developed to screen donors for IgA deficiency and the presence of IgA antibodies. The clinical significance of anti-IgA in individuals who have never been transfused is unclear, because the frequency of antibody detection is much higher than the frequency of severe allergic reactions. This program will summarize some of the difficulties and controversies in this area, the data available from hemovigilance systems regarding severe allergic reactions, new methods available for IgA and anti-IgA screening and issues in setting up a bank of IgA-deficient donors. We will also address investigation and transfusion management for patients with low IgA levels, particularly those with IgA antibodies or a history of severe allergic reactions. Clinical experts from the U.S. and U.K. will discuss patient management issues.