Purpose: Syncope is defined as a transient, self-limited loss of consciousness. The underlying mechanism is a transient global cerebral hypoperfusion. The aim of this study is to prove the efficiency of transcranial doppler study (TCD) with head-up tilt test (HUT) for the diagnostic method of syncope and presyncope in children and adolescents. Methods: We studied 184 patients who were diagnosed with syncope and presyncope at Daegu Fatima Hospital between January 2003 and December 2012. The HUT was performed after a rest at supine for 15 minutes, followed by an 80° tilt test lasting 45minutes. TCD was performed simultaneously in patients underwent HUT. TCD was performed at the middle cerebral artery with 2MHz continuous doppler probe. Systolic, diastolic, mean cerebral blood flow velocity, and pulsatility index were measured with blood pressure and heart rate. Orthostatic hypotension, postural orthostatic tachycardia syndrome and epilepsy were excluded. Results: Among the 184 patients underwent HUT, 120 (65.2%) showed positive result on the test. Eighty eight patients showed a mixed type response, 5 patients showed a cardioinhibitory response, 27 patients showed a vasodepressor response. In ninety six patients out of 184 patients, TCD and HUT was performed simultaneously. Seventy seven patients showed positive result on TCD. Among the 77 patients, 11 (14.3%) showed negative result on HUT, but positive in TCD. Sixty six patients had positive result on both TCD and HUT. Conclusion: TCD with HUT can be a useful diagnostic tool to evaluate syncope and presyncope in the children and adolescents.