Head upright tilt table testing has become an accepted method to measure an individual's predisposition to autonomically mediated periods of hypotension and bradycardia severe enough to cause frank syncope. At the same time it has become increasingly apparent that less profound falls in blood pressure, while not sufficient to result in loss of consciousness, may cause symptoms such as near syncope, vertigo, and dizziness. We describe a subgroup of adolescents that have a mild form of autonomic dysfunction that exhibit disabling symptoms such as postural tachycardia and palpitations, extreme fatigue, lightheadedness, exercise intolerance, and cognitive impairment. During baseline tilt table testing at a 70° angle, these patients demonstrated a heart rate increase of ≥30 beats/min (or a maximum heart rate of ≥120 beats/min) within the first 10 minutes upright (not associated with profound hypotension), which reproduced their clinical symptom complex. Similar observations have been made in the adult population and has been termed the postural orthostatic tachycardia syndrome (POTS). We report that POTS may also occur in adolescents and represents a mild, potentially treatable form of autonomic dysfunction that can be readily identified during head upright tilt table testing.