Background: It remains to be determined whether acute inducibility test of atrial tachyarrhythmias (ATs) immediately after catheter ablation of atrial fibrillation (AF) could be used to assess procedure success or to predict future clinical outcome. Methods: We determined the clinical outcome according to inducibility of ATs at the end of ablation procedure in 81 patients with paroxysmal AF (n=53) and persistent AF (n=28). All patients underwent anatomical left atrial ablation combining electrical isolation of all pulmonary veins guided by 3-dimensional mapping system (NavX or ESI 3000) and circular mapping catheter. Inducibility was tested by burst atrial pacing (10 seconds, 10 mA) from 2 different sites at a cycle length of 250 ms and reducing by 10-ms intervals until atrial refractoriness or 180 ms. Non-inducibility was defined as spontaneously termination of induced ATs within 10 minutes. If ATs lasted longer than 10 minutes, isoproterenol was infused (5 µg/min) and ATs were DC cardioverted with two 10-bipole catheters at right atrium and coronary sinus, respectively. Then, immediate re-initiation of AF (IRAF) was provocated twice. Results: At the end of procedure, 41 (50.6%) patients were non-inducible of any ATs, 35 (43.2%) were inducible but no IRAF, and 5 (6.2%) were inducible and had IRAF. During a mean follow up of 11.4짹3.8 months, non-inducibility was significantly associated with the long-term arrhythmia free rate without the use of antiarrhythmics (35/41, 85.4%) compared with inducible but no IRAF (23/35, 65.7%) and having IRAF (2/5, 40%, P=0.03). Conclusions: After catheter ablation of AF, inducibility test is useful to predict long-term clinical outcome. Non-inducibility of any ATs indicated effective elimination of the triggers and sufficient substrate modification.