Bone pathology was studied in 27 patients showing either iron or aluminium accumulation in bone. These patients belonged to a group of 120 unselected chronic haemodialysis patients in whom transiliac bone biopsies had been obtained. Group A consisted of 12 patients with bone iron deposits (positive Perls' staining at the calcified bone boundary, CBB) and only minimal aluminium accumulation (bone aluminium below 20 micrograms/g wet weight). Group B included 15 patients with pronounced aluminium accumulation (positive aluminium staining at the CBB and bone aluminium of 20 micrograms/g wet weight or more) and without significant bone iron deposition (negative Perls' staining at the CBB). Bone diseases were classified as early hyperparathyroidism, osteitis fibrosa, mixed disease, osteomalacia, adynamic bone disease or other bone condition using osteoid volume, relative osteoblastic activity (ROBA%), and the presence of fibrosis, as criteria. In group A, 5 of 12 patients showed adynamic bone disease, a fairly uncommon condition in the general population of non-parathyroidectomised dialysis patients. In fact, in a control group of 80 patients without iron and without aluminium overload, only five patients showed adynamic bone disease. In group B, 8 of 15 patients showed osteomalacia, and 2 of 15 presented with mixed disease, which is in agreement with the established relationship between bone aluminium accumulation and the occurrence of defective bone mineralisation. It is concluded that iron overload in dialysis patients is associated with an increased frequency of adynamic bone disease.