SummaryBackground: The incidence of syncope increases with age, while aging is also associated with increased arterial wave reflection.Hypothesis: The study was undertaken to determine whether increased arterial wave reflection is a predisposing factor of syncope.Methods: We recruited 38 patients (28 men and 10 women, mean age 57.2 f 20.3 years, range 17-87 years) with a history of syncope within 6 months of entry. The etiology of syncope was documented for each patient by a complete assessment of vasomotor function and cerebral flow. All patients received a comprehensive echocardiographic evaluation of cardiac structure and function. Carotid augmentation index (AI) was estimated noninvasively with the tonometry technique. The results were compared with those from 54 ageand gender-matched controls.Results: The most frequent diagnoses of syncope were postural hypotension (1 3 patients) and cerebrovascular dysautoregulation (10 patients), and the cause could not be determined in 9 patients. Compared with the control group, the syncope group had a greater A1 (20 k 21 vs. 10 k 15%, p =