Passenger lymphocyte syndrome is a rare presentation of posttransplant anemia caused by donor antibodies that target recipient red blood cells. We present a classic case of passenger lymphocyte syndrome in a liver transplant recipient who developed anemia due to immune-mediated hemolysis. He presented 3 weeks posttransplant with shortness of breath and fatigue and was found to have severe anemia with a significant reduction in hemoglobin levels. Evaluation revealed antibody-mediated hemolysis consistent with the diagnosis of passenger lymphocyte syndrome. For these patients, treatment is mainly supportive; however, steroid treatment can be considered. Although rare, passenger lymphocyte syndrome should be part of the differential diagnosis when evaluating posttransplant anemia.