A 48-year-old man diagnosed with multiorgan failure and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pneumonia developed anemia and polyclonal cold agglutinins that reacted at 37 °C. He recovered after a 2-month hospitalization where he received intensive care support. Cold agglutinins resolved after 2 weeks of supportive care. As red blood cell (RBC) cryptic antigens and warm type autoimmune hemolysis have been recently described in coronavirus disease 2019 (COVID-19) patients, we believe this mechanism may also give rise of clinically detectable cold immunoglobulin M (IgM) autoantibodies. Given the thermal amplitude of this particular agglutinin we believe it is possible that in vivo RBC agglutination could contribute to disease severity.