Trismus, or masseter hypertonia, that results from the use of succinylcholine during induction of anesthesia is a rare and dangerous phenomenon. It presents to the anesthesiologist the immediate problem of airway management but it also must be recognized by the physician as a harbinger of malignant hyperthermia. We report a case of induction trismus and discuss its association with malignant hyperthermia. The pathophysiology, diagnosis and treatment of malignant hyperthermia are reviewed.