External direct current (DC) cardioversion refers to the application of a synchronized electrical shock across a patient's chest using a defibrillator. The aim being to convert abnormal tachyarrhythmias back into sinus rhythm. Anaesthetists are often requested to provide anaesthesia for cardioversion because it is an extremely stimulating and painful procedure, which requires an appropriate depth of anaesthesia to be tolerated without adverse psychological consequences. 1 This may involve emergency scenarios in unfamiliar locations such as Coronary Care Units (CCUs) and Emergency Departments, as well as the more commonly performed elective case. Anaesthetists may also need to perform cardioversion themselves in theatre or Critical Care settings. An understanding of both the theoretical and practical aspects of this procedure are essential to perform cardioversion safely and hence form the basis of this review.