The long QT syndrome is a disorder of myocardial electrical conduction that leaves the heart vulnerable to the ventricular tachydysrhythmia torsade de pointes. Clinically, this results in syncope or sudden death. The long QT syndrome may be congenital, if caused by abnormal myocardial potassium or sodium ion channels, or acquired, if due to drugs, electrolyte abnormalities or metabolic conditions. Triggers for the development of torsade de pointes include both anaesthesia and surgery. Some anaesthetic agents prolong the QT interval. The condition is reviewed and suggestions are made for the anaesthetic management of affected patients.