To the Editor. —An article by Diaz et al1in the August Archives warns about transfusion hemolysis in patients who have cold autoagglutinins and undergo hypothermia during cardiac surgery. The authors suggest a pretransfusion test schema because several cold-mediated complications have now been encountered in such patients. Their suggestion is unwarranted. The authors contribute no record of any such complications, but rather cite four articles from the literature. In one of those four reports there was no complication. Another was an article from 1947 on the hemolytic anemia of primary atypical pneumonia. The third report was about a precipitating cryoglobulin in lymphoma. In only one article was there hemagglutinin, cardiac surgery, and hypothermia. As an author of that fourth report,2I know that it concerns not cold autoagglutinins, but an anti-HI that destroyed A2B donor red blood cells in an A1B patient. We stated: