A major challenge in the management of primary hyperparathyroidism (pHPT) is the decision regarding which patients should undergo parathyroidectomy (PTX). although the Consensus Development Conference of the National Institutes of Health (NIH) has proposed guidelines for the indication of surgery. We found that PTX brings about increases in radial and lumbar BMD values as high as 10% in virtually all pHPT patients including postmenopausal women and those without an indication for surgery based on NIH criteria. Serum alkaline phosphatase (ALP) level and the severity of cortical bone mass reduction are clinically useful for predicting the changes in lumbar BMD after PTX. The present findings provide a useful clue for the indication of surgery in pHPT, and seem to warrant a more extended indication than that of the NIH. We also described the recent progress in studies on calcium-sensing receptor (CaR), and discussed the possibility of bone mass recovery by medical treatment of pHPT with a newly introduced CaR agonist ('calcimimetics').