Radiofrequency catheter ablation techniques have enjoyed successful applications in patients with a wide variety of supraventricular tachycardias, especially the Wolff-Parkinson-White syndrome and atrioventricular nodal reentry. More recent reports have shown successful applications in patients with atrial tachycardias and atrial flutter. In addition to these, there are now reports of success during attempts to use radiofrequency techniques to eliminate ventricular tachycardia (VT), both in patients without structural heart disease (idiopathic VT) and patients with structural heart disease (primarily coronary artery disease). Techniques to map sites for ablation in patients with idiopathic VT usually include identifying early endocardial activation and using pace mapping. Success rates for ablation of idiopathic VT have been very high (over 90%) in patients with VT arising from the right ventricular outflow tract. Success rates have not been quite as high when VTs arising from sites other than the right ventricular outflow tract are targeted in the patient with idiopathic VT. In patients with VT caused by coronary artery disease, early endocardial activation and pace mapping can be unreliable. In these patients, searching for mid-diastolic potentials or showing concealed entrainment have proved more reliable. When these latter techniques are applied, success rates in eliminating a single focus of VT in a patient with coronary artery disease has been reported to be as high as 60% to 80%. Future therapies will include new energy sources, new (larger and/or cooled) electrodes, and multipoint catheter mapping, possibly using body surface mapping techniques.