Syncope combines loss of consciousness and inability to maintain postural tone. Prevalence in the subjects aged of 70 years and older is near 30%. In most cases, several causes lead to syncope. The main mechanisms are heart disease, dysautonomy and miscellaneous conditions like anemia varicosis, or drugs with anticholinergic effects. Anamnesis and physical examination lead to the diagnosis in up to 50%. The decision for further diagnostic tests often depends on the evidence of an underlying heart disease. Blood tests, ECG and search of arterial hypotension must be systematically performed. In absence of diagnosis, prolonged ECG monitoring and echocardiography, are the second step exploration. Then tilt test, cardiac electrophysiological study, electroencephalogram may be discussed according to the efficient strategy for the patient. The most important step is to diagnose heart disease because the mortality is doubled in these cases. About 10% of syncopes remained unexplained in the elderly. But their prognosis is not significantly different from that of syncopes of non cardiac origin. So there is no reason to perform invasive explorations to discover etiology in this context. For elderly patients admitted in an emergency ward, the San Francisco Rule aids physician's decision making and performs better than current physician performance to predict prognosis in the first week after syncope. Protocol care must to be developed in geriatric institutions to increase the quality of diagnosis and treatment of elderly subjects after loss of consciousness.