Although drug therapy is often effective for the treatment of supraventricular arrhythmias, radiofrequency catheter ablation is assuming an increasing role for the treatment of cardiac arrhythmias. With a record of high efficacy and low risk of complications, radiofrequency catheter ablations can be considered an alternative to drug therapy for many arrhythmias. Standard radiofrequency catheter ablation involves delivery of an alternating electrical current from a catheter-mounted electrode to a ground pad placed on the skin over the thorax. Resistive heating occurs at the tissue-electrode interface. Several factors determine the temperature achieved during radiofrequency current application and the volume of tissue ablated including the power applied, the duration of current application, the orientation and pressure of the electrode against the myocardium, the blood flow surrounding the electrode, the catheter size, and the perfusion of the tissue. Generally, irreversible tissue injury occurs at a temperature greater than 48°C. Radiofrequency current is routinely used, with an expected success rate of more than 95% for treatment for accessory pathways, atrioventricular nodal reentrant tachycardia, atrial tachycardia, and atrial flutter. The risk of recurrence of these arrhythmias is somewhat higher for patients with atrial flutter or atrial tachycardia than for those with atrioventricular nodal reentry or accessory pathways. The risk of serious complications is approximately 1%. Improvements in technology are likely to allow a curative approach to atrial fibrillation using radiofrequency current delivery for selected individuals.