An otherwise healthy 13 year old developed hypercarbia and increased temperature during anesthesia with sevoflurane. Discontinuation of sevoflurane, surface cooling, and hyperventilation resulted in prompt resolution. However, hyperkalemia continued to raise the suspicion for malignant hyperthermia, which was ultimately confirmed by ryanodine receptor gene sequencing. The case underlines the importance of intraoperative monitoring of end-tidal CO2 and temperature and the potential benefits of early discontinuation of inhalational anesthetics in the presence of signs and symptoms suspicious for malignant hyperthermia. The severe hyperkalemia suggests that standard guidelines for diagnosis and treatment of malignant hyperthermia, including dantrolene treatment, should be followed whenever malignant hyperthermia is suspected.