Cardioversion (CV) is a procedure consisting of 2 different applications, electrical or medical, performed to provide normal sinus rhythm in arrhythmic events. Electrical cardioversion is the preferred direct current-mediated treatment for arrhythmia without sinus rhythm when there is no response to pharmacological therapy or hemodynamic instability due to tachycardia. The difference between defibrillation and electrical cardioversion; in electrical cardioversion, direct current is given on the R or S wave in the QRS by synchronizing with electrocardiography, and in defibrillation, it is given at any moment of the cardiac cycle. Atrial fibrillation and flutter are the most common arrhythmias in which cardioversion is used. Electrical cardioversion should not be performed in patients with ventricular fibrillation, pulseless ventricular tachycardia and digital poisoning. After cardioversion, temporary ST segment elevations, thromboembolism, ventricular fibrillation, short-term bradycardia/asystole, hypotension, pulmonary edema and elevation of cardiac enzymes that do not constitute clinical significance can be observed.