Studies have reported a high prevalence of psychiatric illness in patients with syncope, particularly among those with syncope of unknown etiology. Although mortality rates for patients with syncope and psychiatric disorders tend to be lower than for patients with cardiac cause for syncope, treatment of these psychiatric illnesses appears to result in lower rates of recurrence of the symptoms. The authors recommend an assessment for psychiatric illness in those patients in whom the initial evaluation does not suggest an organic cause for syncope. Further studies are needed to elucidate the pathophysiologic mechanisms for syncope and the effects of treatment of psychiatric illness on recurrence of syncope.