Malignant hyperthermia (MH) is a rare but potentially life-threatening disorder encountered during general anesthesia. The use of cardiopulmonary bypass during cardiac surgery can obscure many of the cardinal signs and symptoms of MH. The development of postoperative MH following cardiac surgery is rare, but anesthesiologists and intensivists must maintain a high index of suspicion in order to make a prompt diagnosis. Initiation and tailored maintenance of MH therapy must also consider the complex physiologic changes of patients in the immediate post–cardiac surgery period. In this article, we present a case of the development of postoperative MH in the cardiac intensive care unit after elective open heart surgery with cardiopulmonary bypass.