A 59-year-old female developed acute autonomic failure accompanied by life-threatening orthostatic hypotension. Reduced plasma noradrenaline levels and enhanced pressure response to noradrenaline infusion were compatible with a diagnosis of acute pan-dysautonomia. However, nerve conduction tests clearly revealed motor and sensory nerve involvement and abnormal F-responses. A sural nerve biopsy and catecholamine fluorescence study of the rectal mucosa revealed relatively preserved postganglionic unmyelinated nerve fibers. Six weeks later, the patient developed another episode of bulbar palsy and right hemiparesis; the MRI showed lesions in the medulla oblongata and right cervical spinal cord. The prognosis of acute pan-dysautonomia is usually unsatisfactory, but the present patient showed good steroid-responsiveness probably because impaired preganglionic sympathetic myelinated fibers and medulla oblongata recovered quickly.