The short shelf life of platelets makes providing ABO-compatible platelets a challenge, and many institutions issue ABO-incompatible platelets when compatible units are not available. It is presumed that ABO antibodies that exist in donor plasma are diluted when platelets from multiple donors are combined to make a pooled product for transfusion. We present a case of a hemolytic transfusion reaction in a 73-year-old man with myelodysplastic syndrome who received an ABO-incompatible pooled platelet unit. This case report demonstrates that the dilution theory is not always true for pooled platelet units, and any patient receiving ABO-incompatible platelet transfusions must be closely monitored for potential hemolytic transfusion reactions.