AIM: Primary hyperparathyroidism (PHPT) is one of main cause of morbidity in patients with multiple endocrine neoplasia type 1 (MEN1). Medical therapy with cinacalcet-hydrochloride may modify the therapeutic strategy of MEN1 related PHPT. We present an experience with cinacalcet-hydrochloride in two patients with MEN1 PHPT. METHODS: The study included two MEN1 patients belonging to the same family (a 50-year-old woman and her daughter aged 20 years) with PHPT secondary to multiple involvement of parathyroid glands and other MEN1 related tumors. As both patients refused to undergo parathyroid surgery, we decided to start medical treatment with cinacalcet at the dose of 30 mg/day, which was the first treatment for the youngest patient, while the oldest had already been treated with partial parathyroidectomy. Serum concentrations of PTH, calcium and phosphorus, 24-h urine calcium-to-creatinine ratio and renal-threshold-phosphate concentration were evaluated before and after therapy. RESULTS: Serum calcium and PTH levels were normalized after 1 and 6 months of therapy, respectively, and 60 and 54 months after the beginning of cinacalcet remained normal. Hypercalciuria, hypophosphoremia and renal-threshold-phosphate normalized during therapy with cinacalcet. At ultrasonography, parathyroid nodular lesion remained unchanged. Cinacalcet was well tolerated without occurrence of side effects. CONCLUSION: Cinacalcet seems to be highly effective in controlling PHPT in patients with MEN1 either in naïve patients or in those with postsurgical recurrence. If cinacalcet will be confirmed to ensure a long-time control of PHPT or even to prevent the development and progression of PHPT, this may led to modify the therapeutic strategy of MEN1 PHPT.