Culture supernatants of tenosynovial tissues from patients with carpal tunnel syndrome undergoing chronic haemodialysis contained interleukin (IL) 1-like and IL6-like activity. These culture supernatants also induced active proliferation of rheumatoid synovial cells. Immunohistochemical analysis of teno-synovial tissues showed the accumulation of mononuclear cells bearing CD14 and HLA-DR antigens adjacent to the deposition of amyloid protein (beta 2 microglobulin). These cells also reacted with antibodies to IL1 and IL6 respectively. These data suggest that multiple cytokines, including IL1 and IL6, produced from tenosynovial tissues in patients with dialysis associated amyloidosis might induce the proliferation of synovial cells that, together with deposition of amyloid protein, might cause carpal tunnel syndrome.