A search for visceral amyloid deposits was performed on autopsy material from 20 patients who had been receiving long-term hemodialysis treatment for 4 to 21 years. Visceral amyloid was found in seven patients who had undergone hemodialysis for more than 10 years. Histochemically, the amyloid was permanganate sensitive, and immunohistochemically, it stained positively for beta 2-microglobulin. The amyloid was found mainly in the wall of blood vessels, in the form of subendothelial nodules, bulging into the vessel's lumen. The amount of amyloid increased with increasing years of hemodialysis treatment. The organs most frequently involved were the heart, gastrointestinal tract, and lungs. Smaller deposits were seen in medium blood vessels of all other visceral organs. Only the spleen was "resistant" to amyloid deposition; the reason for this splenic resistance is unknown. A similar organ distribution was found in the 19 previously reported autopsy cases. Clinically, one patient experienced a perforation of the small intestine, probably related to the narrowing of the intestinal blood vessels by amyloid deposits, and this patient died of peritonitis.