Transfusion-related acute lung injury (TRALI) is an uncommon life-threatening complication of hemotherapy. It is hypothesized to be the result of two independent insults: the first related to the clinical status of the patient and the second to the infusion of biologic response modifiers within blood components. We present a case of TRALI in a patient who received high-dose Interleukin-2 (IL-2) as treatment for metastatic renal cell carcinoma, where IL-2 is speculated to have been the first insult and transfusion of platelet concentrate the second. This is the first reported case of TRALI complicating treatment with high-dose immunotherapy.