Cinacalcet, a calcimimetic, was evaluated in persistent hyperparathyroidism after kidney transplantation (Tx). Ten kidney transplant recipients and one kidney-pancreas recipient with persistent post-Tx hypercalcemia (serum calcium [SCa]>> 10.2 mg/dl), stable graft function, and intact parathyroid hormone (iPTH)>> or = 2 times normal received 30 mg/d cinacalcet between 2 mo and 5 yr after Tx. SCa, serum phosphorus (SP), and iPTH were measured before and after cinacalcet. Mean pre-cinacalcet SCa was 10.9 mg/dl (8.6 to 11.9 mg/dl). Average pre-cinacalcet SP was 2.9 mg/dl (1.8 to 4.0 mg/dl). Mean pre-cinacalcet iPTH was 267.0 pg/ml (99 to 723 pg/ml). After cinacalcet, SCa decreased on average by 1.6 mg/dl (95% confidence interval 1.2 to 2.1; P < 0.0001). Post-cinacalcet SP increased on average 0.45 mg/dl (P = 0.046). Post-cinacalcet iPTH averaged 156.9 mg/dl (P = 0.10). Graft function remained stable. Cinacalcet lowers SCa and raises SP in the short term in patients with persistent post-Tx hyperparathyroidism; long-term bone effects and persistent hyperparathyroidism merit further study.