In order to assess the diagnostic value of invasive electrophysiologic study (EPS) in thepatients with unexplained syncope, the electrophysiologic findings of 268 patients with unexplainedsyncope despite a complete clinical evaluation were analyzed. Results showed positive EPS findingwas 38% in total patients and S0% in the patients aged ＞70 years. With increasing age, the diag-nostic yield of EPS also increased. No significant differences of complication rate were found amongthe different age groups. It was concluded that EPS havd high diagnostic value in the patients withunexplained syncope. Its complications are few and mild. EPS may be recommended in elderly pa-tients with unexplained syncope.