Double tachycardia appears to be relatively rare. Our single-center experience of coincident typical atrioventricular nodal reentrant and idiopathic ventricular tachycardia was reviewed. Between September 2003 and February 2005, 40 patients with idiopathic ventricular tachycardia underwent catheter ablation for right ventricular outflow tract tachycardia in 20, left ventricular outflow tract tachycardia in 2, and left ventricular septal tachycardia in 18. In 5 patients (2 men and 3 women, aged 27-49 years) there was a combination of typical atrioventricular nodal reentrant tachycardia and idiopathic ventricular tachycardia. They had no structural heart disease. The presenting arrhythmia was supraventricular in one and ventricular in 4. There was no case of inducibility of one arrhythmia by the other (tachycardia-induced tachycardia), but an interaction was observed in one tachycardia in which inducibility was seen only after ablation of the other arrhythmia. Radiofrequency ablation of either arrhythmia did not prevent induction of the other.