The purpose of this prospective study was to analyze the natural history of patients with clinical neurocardiogenic syncope. The results obtained with some therapeutic strategies in the prevention of neurocardiogenic syncope are encouraging. However, the benefit they represent when compared with the natural history of syncope has not been clearly established. Fifty-six consecutive patients with either (1) one or more episodes of syncope and a positive head-up tilt test or (2) typical history of vasovagal syncope despite a negative tilt test were monitored during a mean period of 16.1 +/- 10.2 months. Patients were discharged without any specific medication. There were no deaths during the follow-up period. Recurrences were found in 5 (8.9%) patients. The risk of recurrence was 7% after 1 year and 15% after 21 months. The prognosis of patients with clinical neurocardiogenic syncope is excellent as far as survival is concerned. Recurrences of episodes without specific treatment were uncommon after diagnosis had taken place. This finding strengthens the need to evaluate the effect of drugs with placebo control groups and to select the highest-risk group for treatment.