Background: Hyperparathyroidism is a common disorder associated with a defect in metabolism of calcium and phosphorus in the body. Of the serious complications of the disease are pathologic fractures and brown tumours. Patients and methods: We herein study retrospectively the patients with hyperparathyroidism who underwent surgical treatment at a tertiary hospital during a 12-year period. Results: 36 patients were enrolled in this study. The majority of the patients were females, the mean age was 46 years old. Pathologic fractures and brown tumours were present in about 14% of the patients each, while postoperative hypocalcaemia occurred in about 11% of the patients. In addition, we detected that the higher the serum calcium level on presentation the higher the chance to develop pathologic fracture or brown tumour, while there was an increased chance of having a post-resection hypocalcaemia with higher levels of parathormone hormone. Conclusion: Patients with high serum calcium level, especially shooting levels should be recommended a surgery as of fracture and brown tumour risk. Also, the higher the level of parathormone, the more need for rigorous monitoring of serum calcium after surgery.