Parathyroid cells can sense small changes in plasma Ca2+ levels by virtue of a cell surface Ca2+ receptor. Calcimimetics are newly synthesized compounds that act as agonists or positive allosteric modulators at the Ca2+ receptor and can suppress parathyroid hormone secretion. The first-generation calcimimetic, NPS R-568, has undergone clinical trials in primary hyperparathyroidism and in hyperparathyroidism secondary to chronic renal insufficiency. The data accumulated so far demonstrate that calcimimetics have potential as therapeutic agents for hyperparathyroidism and related bone diseases such as osteitis fibrosa.