A case was described with fast-slow form of atrioventricular nodal reentrant tachycardia as related with simultaneous fast and slow pathway conduction both antegrade and retrograde. Fast-slow form of tachycardia was induced by premature right atrial stimulation or incremental right ventricular pacing when the last paced beat conducted to the atria via both fast and slow pathways of the atrioventricular node causing double atrial response. Fast-slow form of tachycardia was spontaneously shifted to slow-fast form when the atrial echo, possibly through the retrograde intermediate pathway, was conducted antegradely over the fast and slow pathways simultaneously, producing double ventricular response.