The influence of hyperparathyroidism and aluminium toxicity on bone scan scores (FS = Fogelman's score) was studied in 37 haemodialysis patients (group 1), of whom 24 had aluminium toxicity (group 2). FS, parathormone (iPTH) and aluminium status were assessed simultaneously, the latter by measuring serum aluminium before (BAl) and 48 hours after (PAl) a desferrioxamine infusion. FS correlated directly with iPTH in all groups, inversely with PAl and DAl (= PAl - BAl) in group 1; FS less than or equal to 2 was found in group 2 only (2 alpha less than 0.05). The time course of FS and aluminium concentration was also studied in 24 patients: a PAl increase was significantly associated with a FS decrease (2 alpha less than 0.001). In conclusion, hyperparathyroidism increases and aluminium toxicity decreases FS; FS less than or equal to 2 is very suggestive of aluminium toxicity.