Syncope is a symptom, not a disease. The potential causes of syncope are myriad and range from the fairly benign to the potentially life-threatening. To rule out the more dangerous causes, including cardiac arrhythmias, patients often undergo an exhaustive, expensive, and potentially invasive battery of diagnostic tests. Research to improve the workup of syncope is hampered by the transient nature of the condition and the lack of a diagnostic gold standard with which to assess the sensitivity and specificity of different testing modalities. Studies in the 1980s and 1990s have provided information regarding the yield of different tests in various patient populations and the prognostic significance of various clinical and epidemiologic markers. This article focuses on the evaluation of patients with syncope, including the utility of and indications for different diagnostic tests, the indications for hospital admission, and the management of patients with certain known causes of syncope, including vasovagal and arrhythmic.