Background: Atrial fibrillation(AF) is selectively treated with catheter ablation when a patient have 2 or more antiarrhythmic agent failure. However, high recurrence rate often problematic. therefore, predictor of success of catheter ablation was important. Magnetocardiography (MCG) is a non-invasive and risk-free technique allowing body surface recording of the magnetic fields generated by the electrical activity of the heart. The MCG recording system allows spatially and temporally accurate measurement of the very weak magnetic fields produced by currents flowing within myocardial fibers during cardiac activity. So, we studied whether the MCG can be helpful in the prediction of AF recurrence Methods: We analyzed the initial MCG in 36 patients having paroxysmal AF, admitted to our institution between Mar 2005 and Sep 2007. The patients Five MCG parameters on p wave and ECG findings were analyzed. Results: Fig 1. Patient Characteristics (n=36)