BACKGROUND: Few studies have reported changes of bone mineral density (BMD) after parathyroidectomy in patients with persistent hyperparathyroidism after renal transplantation (3 HPT). PATIENTS AND METHODS: We retrospectively analyzed 14 patients who underwent successful parathyroidectomy for 3 HPT and who had available BMD data before and after parathyroidectomy. RESULTS: Median follow-up time was 26 months (IQR: 16.8-40.2). Serum calcium levels decreased significantly after parathyroidectomy (2.32 +/- 0.09 versus 2.66 +/- 0.16 mmol/l; p < 0.01), as did PTH levels (5.1 +/- 3.0 versus 27.8 +/- 23.7 pmol/l; p < 0.01). Nine patients (64%) had a steroid-free immunosuppression at follow-up. Mean increase in BMD was 9.5 +/- 8.0% for the spine and 9.5 +/- 7.9% for the hip (p < 0.01 for both sites). Patients with osteoporosis (T-score