~20 y/o AAF. O Positive. Positive antibody screen 3-cell screen. All cells positive. First panel (Ortho A panel) all cells positive but autocontrol negative. All testing in gel. Ortho B panel has some rule outs and some positive cells. Immucor resolve 3% panel cells converted to gel, we get a few more rule outs and positive cells. We identify anti-Fy(a), anti-K, anti-C and some antibody of undetermined specificity in the patient's plasma. We get history from the patient, they had been transfused 5 days before. We call the transfusing hospital. They had identified anti-Fy(a) and anti-K and transfused 4 Fy(a) and K neg units. We do tube testing and find that the anti-C reacts at both immediate-spin and 37C. DAT panel Polyspecific: 1+ Monospecific IgG: 0* anti-C3: 1+ sal ctrl: 0 An eluate is performed and anti-Fy(a) and anti-K are identified from the panel. 2 Fy(a)/K-neg C+ panel cells react 1+ but 3 others do not. One Fy(a)/K/C-neg cell that reacts in the plasma and has been reacting in various other patients reacted in the eluate. Patient has high fever (102-103F+), hemoglobinuria and generalized body ache. Patient's plasma was grossly icteric, LDH and Bili both high. Reportedly the patient experienced severe flank pain during the transfusion itself but was discharged that same day. Patient's hgb has plummeted since admission.