Malignant hyperthermia is a hypermetabolic disorder of skelectal muscle. It goes fatal progress in the majority of cases unless early diagnosis and treatment are performed. We experienced two cases of malignant hyperthermia during general anesthesia. First case is 7-year-old boy with congenital bilateral ptosis. Second case is 46-year-old male with lung cancer. We were faced to difficult intubation due to masseter muscle spasm. After induction, tachycardia, muscle rigidity, body temperature elevation, end tidal CO2 elevation and acidosis developed. Enflurane was discontinued, vigorous emergency treatment was attempted. Fortunately, two patients were recovered from malignant hyperthermia and then discharged without complications.