ABSTRACT. We report a peculiar case of recurrent hyperparathyroidism caused by hyperplasia of a forearm graft implanted following a total parathyroidectomy in a 38-year-old patient with chronic renal failure. The forearm graft hyperplasia was detected using 99 Tc m -sestamibi scanning, which identified hyperplastic transplanted parathyroid tissue in the forearm of the patient. During the initial surgery, the surgeon failed to mark the parathyroid tissue with sutures or clips to facilitate locating it. Therefore, we referred the patient for radioguided surgery. This surgical procedure allowed us to locate and completely remove the hyperfunctioning transplanted parathyroid tissue.