We report the first case of acute autonomic, motor and sensory neuropathy (AASMN) associated with meningoencephalitis. A 62-year-old man presented with fever, neck stiffness, and coma. Respiratory failure developed. Magnetic resonance images showed an abnormality in the medial temporal lobe. Cerebrospinal fluid analysis revealed pleocytosis with a high protein level. Intensive care gradually improved the consciousness level, but paralysis of the four extremities persisted. Nerve conduction studies revealed demyelinating sensory and motor polyneuropathy. Severe orthostatic hypotension, urinary retention, and constipation were also present. Clinical autonomic tests suggested both sympathetic and parasympathetic dysfunction. After intravenous immunoglobulin therapy, motor and sensory symptoms resolved rapidly; dysautonomia resolved gradually over the next 2 months. The response to immunological therapy and the presence of antecedent infection suggest that AASMN is a postinfectious, immune-mediated, autonomic, sensory and motor nervous system dysfunction.