A 37-year-old man with acquired generalized anhidrosis but without other autonomic or somatic abnormalities (idiopathic acquired generalized anhidrosis) is described with special reference to histologic and morphometric findings of the eccrine gland and its nerve terminals and unmyelinated axons. The patient was admitted to our hospital in August 1989 with complaints of heat intolerance and anhidrosis of the face, trunk, and both limbs. General physical and neurological examinations revealed no abnormalities except generalized anhidrosis. Sweating tests revealed anhidrosis of most surfaces of the body except the axillae, mammary areolae, forearms, hands, popliteal fossae, and plantar surfaces. Sympathetic skin responses were absent in the axillae, and were decreased on the palms. Iontophoretically applied pilocarpine revealed a complete absence of active eccrine glands on the dorsal surface of the right foot. No other abnormalities were revealed by autonomic function tests. Light and electron microscopic studies of the eccrine glands of the distal and lateral aspects of the left leg were performed in this patient and six control subjects. Infiltration of mononuclear inflammatory cells around the duct and secretory coil of a limited number of eccrine glands on multiple sections was found only in this patient. Electron microscopic morphometric evaluation of the eccrine glands, associated nerve terminals and unmyelinated axons of this patient revealed no definite alterations when compared with those of the six control subjects. Therefore, we concluded that the nerves innervating the eccrine glands were not affected in this patient and suspect that either the cholinergic receptors or the function of secretory cells of the eccrine glands were involved.(ABSTRACT TRUNCATED AT 250 WORDS)