Background : As we reported, AF ablation by MNS is equally effective and much safer than conventional ablation. But it takes long time for learning up, we have had difficulties to get consistent data. According to two year experiences, we compared the advantages and disadvantages between two methods. Subjects and methods : We have ablated 156 AF patients ( Paroxysmal, Persistent and long standing AF patients: 52 , 105 patients ) by MNS, Then we compared and analyzed the procedural parameters such as fluoroscopic time, procedural time and acute success and 8 months success rate with same number of AF patients ablated by manual. The mean follow up period was 12짹 4.2 months. Results : The mean follow up period was 12짹 4.2 months. In paroxysmal atrial fibrillation, total procedure time was significantly longer in MNS than conventional ablation (216짹48min vs. 160짹76min, p = 0.006) but in MNS group, compared to those patients whose LA size is more than 42mm, showed markedly short procedure time ( 278짹69 vs. 177짹41min p < 0.0032 ). Total fluoroscopic time was significantly shorter in MNS than manual group (68 짹25 vs. 107짹60min, p <0.0001). In persistent and long standing atrial fibrillation, total procedure time was insignificantly shorter in MNS group (283짹79 vs. 244짹54min, p = 0.084), but total fluoroscopic time was significantly shorter in MNS than manual ablation (95 짹 15 vs. 196 짹 53, p Value:<0.0001). No cardiac tamponade was shown in MNS group compared to conventional group( 0 vs 3.26% p< 0.001 ). There were no differences in complete antral isolation rate and anterior line block rate. There were no differences in total recurrence rate, atrial fibrillation, Atypical atrial flutter and Atrial tachycardia recurrence rate at 12 months in both paroxysmal and persistent atrial fibrillation. Conclusion : MNS can provide us much safer and effective way of AF ablation especially for those patients who have slightly dilated left atrium.