Synovial amyloid deposits were found in 18 patients with end-stage renal failure due to various nonamyloid nephropathies, who had been treated with long-term, periodic hemodialysis (mean 116 months). All patients had carpal tunnel syndrome, which was bilateral in 14 of them; 4 patients also had finger flexor tenosynovitis. In 2 patients, destructive arthropathies required surgical replacement of the hip. Amyloid deposits were demonstrated by light microscopy in the synovium of the finger flexor tendon and/or transverse carpal ligament of all patients who had surgery for carpal tunnel syndrome, and in the synovium and capsula of the 2 surgically removed hips. Transmission electron microscopy of synovial samples from 6 patients demonstrated the characteristic fibrillar ultrastructure of amyloid deposits, the biochemical nature of which is still unknown. In addition, 9 patients had cystic radiolucencies of bone, which were interpreted as having resulted from local amyloid deposits, involving carpal bones, humeral heads, femoral heads, acetabula, or tibial plateaus. Our results show that amyloidosis is a frequent histologic finding in dialysis patients receiving surgical management of carpal tunnel syndrome, and that it can also be associated with cystic radiolucencies of bones and with destructive arthropathies.