BACKGROUND: Cinacalcet rapidly normalizes serum calcium and reduces intact parathyroid hormone (PTH) levels in renal transplant patients with hypercalcaemia and persistent hyperparathyroidism. The aim of this study is to evaluate the 6 months efficacy of cinacalcet and the effect of cinacalcet withdrawal on serum calcium and PTH in such patients. Furthermore, the impact of cinacalcet on bone turnover and quality of life was assessed. METHODS: Twelve renal allograft recipients with hypercalcaemia due to persistent hyperparathyroidism were treated with cinacalcet for 26 weeks. Cinacalcet was then withdrawn to check for recurrence of hypercalcaemia. RESULTS: Cinacalcet maintained normocalcaemia in all patients from week 4 to 26, and PTH significantly decreased and remained suppressed. Serum phosphate increased, whereas the serum calcium-phosphate product remained unchanged. The excretion of calcium and phosphate in the 24 h urine had tendency to decrease. After cinacalcet was withdrawn, hypercalcaemia recurred rapidly and PTH increased to baseline values. Renal function remained stable, proteinuria was unchanged and no allograft rejection was observed. During treatment with cinacalcet, total and bone-specific alkaline phosphatase increased, whereas the urinary deoxypyridinoline-creatinine ratio did not change significantly, suggesting enhanced bone formation. Quality of life assessed at weeks 10 and 26 remained unchanged compared with baseline. CONCLUSIONS: In conclusion, continued treatment with cinacalcet is required to maintain long-term normocalcaemia and to suppress the enhanced PTH production in renal transplant recipients with persistent hyperparathyroidism.