The diagnosis of persistent or recurrent hyperparathyroidism after total parathyroidectomy with autograft in the forearm needs a correct assessment of graft function. In 6 patients with relapsing hyperparathyroidism after total parathyroidectomy with forearm implant, total ischaemic blockade of the arm bearing the parathyroid graft, produced a 'temporal implantectomy' with reduction of iPTH in those with graft hyperfunction. In 2 patients with proved supernumerary gland, total ischaemia of the 'graft' was not followed by iPTH changes. Total ischaemic blockade of the arm bearing the parathyroid graft is a valuable method for a correct assessment of graft function. It gives useful information in order to avoid or indicate a reoperation of the neck in patients who had previously undergone parathyroidectomy.