Recurrent idiopathic exercise-related syncope in the young athlete is often a challenging and frustrating condition. Vasovagally mediated hypotension and bradycardia is believed to be a common, but difficult to prove, cause of this form of syncope. This study evaluated the usefulness of head-upright tilt table testing in the evaluation and management of young athletes with recurrent idiopathic exercise-related syncope. Twenty-four trained young athletes (12 male, 12 female mean age 18 ± 3.4 yr) with recurrent unexplained exercise-related syncope were evaluated by use of an upright tilt table test for 30 min, with or without an infusion of isoproterenol (1–3 μg. min−1given intravenously) in an effort to provoke bradycardia, hypotension, or both. Ten control patients with no history of syncope were also studied. Syncope occurred in 10 patients (41%) during the baseline tilt and in nine patients (37%) during the isoproterenol infusion (total positives 79%). Seventeen patients who had positive test results eventually became tilt table negative with pharmacotherapy, and over a mean follow-up period of 23 ± 7 months, no further syncopal episodes have occurred. Two patients refused pharmacotherapy and have continued to experience syncope. We conclude that head-upright tilt table testing combined with isoproterenol infusion is useful in the diagnosis of vasovagal syncope in young athletes with recurrent exercise related syncope, and in the evaluation of prophylactic pharmacotherapy.