AbstractA 9‐year‐old boy presented with symptoms and signs of marked postganglionic cholinergic autonomic dysfunction manifested by bilateral internal ophthalmoplegia, impaired secretion of tears and saliva, lack of gastrointestinal motility, atony of the bladder, generalized absence of sweating, and hypertension. Clinical and pharmacological studies confirmed that the abnormalities were restricted mainly to the postganglionic cholinergic autonomic system and showed evidence of postdenervation supersensitivity to parasympathomimetic drugs. The patient was treated in the early phase of his illness by the administration of carbachol, and eventually he made a slow and partial spontaneous recovery. Histoimmunofluorescent studies on a skin biopsy specimen suggested an autoimmune origin for his disease, with IgG antibodies being produced against postganglionic cholinergic autonomic fibers.