Nodal reentrant supraventricular paroxysmal tachycardia corresponds to a reentry circuit established between fibers with different conduction velocities and refractory periods in the atrioventricular node. These are the slow and fast nodal pathways. That ventricular tissue does not form part of the circuit of this arrhythmia is accepted nowadays, and the involvement of atrial tissue is discussed. We report a 57 years old male with a nodal reentrant tachycardia. In the electrophysiological study be presented an atrial and ventricular dissociation during the tachycardia. These findings allow a better understanding of the electrophysiological substrate of this arrhytmia.