Idiopathic ventricular tachycardia is not a single clinical entity. Several electrophysiological mechanisms are responsible for at least two typical electrocardiographical pictures. The tachycardia with right bundle branch block morphology and inferior axis is the most common type and originates in the right ventricular outflow tract. It has to be differentiated from right ventricular dysplasia, and also from tachycardia in association with mitral valve prolapse. It is responsive to calcium antagonists, and can be treated with radiofrequency ablation. The other tachycardia (left bundle branch block morphology and right axis) originates in the posterior left ventricular septum and has typically sharp potentials preceding the ventricular electrogram in the site where ablation is successful. Both types can be associated with different types of cardiomyopathy, and therefore further investigation might be useful.