Familial amyloidosis, Finnish type (FAF), is a gelsolin-related systemic amyloidosis that has an autosomal-dominant inheritance pattern and is clinically characterized by progressive cranial neuropathy, corneal lattice dystrophy and skin changes such as cutis laxa, blepharochalasis, and lichen amyloidosis. A 70-year-old Japanese male proband, who was believed to be originally from Fukuoka Prefecture, showed signs and symptoms characteristic of FAF. In addition, he complained of progressive anhidrosis and heat intolerance during the daytime in summer. On examination, perspiration was absent on the almost entire body surface. Molecular genetic studies showed a G-to-A transversion that resulted in the substitution of asparagine for aspartic acid 187 in the gelsolin gene, a mutation found in most patients with FAF. Skin biopsy revealed marked deposition of amyloid, which was positive with anti-gelsolin antibody staining, around eccrine sweat glands and ducts, and around sebaceous glands, outside the basal lamina; slight to mild deposition around small vessels and small nerve fascicles; and very slight deposition in the perineurium and endoneurium. Morphometric evaluation of the nerve terminals and axons of eccrine sweat glands revealed a significant decrease in the number of nerve terminals per transverse profile of the sweat gland. Compared with controls, nerve terminals were further from the secretory epithelial cell owing to deposition of amyloid outside its basal lamina. The proband's sister had almost identical, although much less severe, clinical signs and symptoms with the same mutation of the gelsolin gene. Autonomic signs and symptoms in FAF are reported to be less frequent and less severe than those in familial amyloid polyneuropathy of Andrade type. Findings in our proband suggest that perspiration may be markedly decreased in FAF owing to marked deposition of amyloid around the eccrine sweat gland which causes degeneration of the nerve terminals and disturbs access of the neurotransmitter to the secretory epithelial cell.