Background: The 12-lead electrocardiogram helps to define the arrhythmic mechanism in patients with palpitations. However in the setting of nondocumented palpitations, the electrophysiologic study (EPS) needs additional investigation. We investigated the utility of the EPS in patients with nondocumented palpitations. Methods: Among 1827 patients who underwent EPS at the Samsung Medical Center in Korea between January, 2004 and December, 2010, we retrospectively analyzed 85 individuals with normal electrocardiographic findings and nondocumented recurrent palpitations. The clinical and electrophysiologic characteristics were assessed. Results: The symptom lasted more than one year in 69%. Sudden onset was present in 92%, and termination was rapid in 61%. 58 patients (68%) showed positive EPS findings; Atrioventricular nodal reentrant tachycardia was induced in 19 (22%), orthodromic reentrant tachycardia in 28 (33%), and sustained atrial tachycardia (AT) in 11 (13%). The long-duration of palpitation (>1 year) and sudden termination were associated with positive EPS findings. The sudden onset and termination can predict the reentrant supraventricular tachycardia (SVT) and Short-lasting episodes (<5 minutes) and association with exercise can predict the atrial tachycardia. All 47 patients with induced reentrant SVT (55%) underwent radiofrequency ablative therapy. The radiofrequency ablation was successful in 100% of cases without any complication. Conclusion: In conclusion, EPS is a feasible with nondocumented palpitations and normal electrocardiographic findings at baseline. Sudden onset and termination of palpitation, short-lasting episodes (<5 minutes) and association with exercise can be helpful history to diagnose tachycardia.