We investigated the etiologies of syncope and risk factors for mortality and rehospitalization for syncope at 17-month follow-up in a prospective study of 242 consecutive patients, mean age 69 years, hospitalized for syncope. The etiologies of syncope included the following: vasovagal syncope in 49 patients (20%), volume depletion in 39 patients (16%), orthostatic hypotension in 13 patients (5%), primary cardiac arrhythmias in 25 patients (10.3%), structural cardiac disease in 6 patients (2%), and drug overdose in 5 patients (2%). The etiology of syncope could not be determined in 84 patients (35%). Of the 242 patients, 6 (2%) were rehospitalized for syncope and 12 (5%) died. Stepwise logistic regression analysis showed that the significant independent prognostic factors for rehospitalization for syncope were drug overdose [odds ratio (OR): 11.506; 95% confidence interval (CI): 1.083-22.261]. Stepwise logistic regression analysis showed that significant independent prognostic factors for time to mortality were undetermined etiology of syncope (OR: 4.665; 95% CI: 1.002, 21.727), San Francisco Syncope Score (OR: 3.537; 95% CI: 1.472-8.496), hypertension (OR: 0.099; 95% CI: 0.019-0.504), and glomerular filtration rate (OR: 0.964; 95% CI: 0.937-0.993).