ORTHOSTATIC hypotension may be primary or secondary. The clinical syndrome of primary idiopathic orthostatic hypotension is characterized by inability to sustain standing blood pressure without the development of pallor or of tachycardia.1Other findings include anhidrosis, impotence, urinary urgency or retention, alternating constipation and diarrhea, and a variety of disturbances directly pointing to disease of the central nervous system.2Evidences of central nervous system disease include dysarthric or monotonous speech, diplopia, pupillary irregularities, vertigo, rigidity, tremor, cerebellar ataxia, and incontinence.2 Orthostatic hypotension, as a secondary phenomenon, occurs in a wide variety of disease states and after bed rest. Interest in orthostatic hypotension has been stimulated by its development after space flights.3Sustained orthostatic hypotension has been described in neuropathies (diabetic,4porphyric,5nutritional), in myasthenia gravis,6in paraplegia of varied causes, in Wernicke's encephalopathy,7,8in combined systems disease,9in tumors of