We are reporting a previously healthy adolescent who developed atrial fibrillation after being tased. He has a structurally normal heart on echocardiogram, normal electrolyte level and thyroid function test results, and a urine toxicology screen positive for marijuana. The patient ultimately required external defibrillation to convert his cardiac rhythm to normal sinus rhythm and has had no recurrent arrhythmias since hospital discharge (approximately 1 year). This is the first reported case of atrial fibrillation developing after a Taser shot, occurring in an adolescent without other risk factors. This case illustrates the arrhythmogenic potential of a Taser in otherwise healthy young individuals, and further study of occurrence of Taser-induced arrhythmias is warranted.