A 5-year-old girl susceptible to malignant hyperthermia underwent total repair of tetralogy of Fallot. The initial operation was canceled because of abrupt hyperthermia and metabolic acidosis of unknown cause. Dantrolene was given orally as preoperative treatment and administered intermittently during surgery. Postoperative hyperthermic crisis was successfully treated with intravenous dantrolene combined with surface cooling, gastric tube irrigation with cold saline, and alcohol vaporization.