We report a 20-year-old sportsman with frequent attacks of lightheadedness, chest pain, blurred vision and falls during and shortly after exercise. Cardiac and pulmonal evaluation and routine autonomic function tests were normal apart from a relatively high resting heart rate (70 bpm) compared to endurance-trained men. In view of the relation to exercise, the patient was asked to cycle with maximal effort on an ergometer with continuous blood pressure (BP), heart rate (HR) and electroencephalogram (EEG) registration. Immediately after cessation of exercise a brief hypotensive period (75/45 mmHg) occurred together with sinus tachycardia (180 bpm) during which the patient experienced his typical complaints. We hypothesized that our patient's symptoms were primary related to sympathetic failure. As water drinking has been demonstrated to raise sympathetic activity rapidly, we undertook a second cycling test after ingestion of 1000 mL tap water. Symptoms nor hypotension recurred. Because of the short lasting pressor effect and its minimal side effects, we suggest water drinking as simple and possible effective therapy for idiopathic exercise-related syncope.