 The autonomic nervous system has a central role in the regulation of blood pressure. Primary Autonomic Failure is manifested in a variety of syndromes. Orthostatic hypotension is a usual presenting symptom. Primary Autonomic Failure may be the primary diagnosis, and classifications include pure autonomic failure PAF, also called idiopathic orthostatic hypotension Bradbury-Eggleston syndrome autonomic failure with multiple system atrophy Shy-Drager syndrome and also Parkinsons disease. Regardless of the primary condition, autonomic dysfunction underlies orthostatic hypotension. 