Introduction: Primary hyperparathyroidism(PHPT) is extremely rare in children and adolescents. Parathyroid adenoma is the most common etiology for PHPT. Hungry bone syndrome (HBS) is an entity encountered in the postoperative period following parathyroid adenoma removal. We present two cases of PHPT presented as bone deformities and the management complicated by HBS. Case presentation: Patient A - A 13-year-old girl presented with a three-month history of abnormal gait, left-sided genu varum, leg-length discrepancy , and postural scoliosis. Investigations revealed hypercalcemia with elevated parathyroid hormone(PTH) levels. Neck ultrasonography and Tc-99m MIBI scan confirmed a parathyroid adenoma. She receivedpreoperative cinacalcet and zoledronate, followed by surgical excision. Postoperatively , she developed symptomatic hypocalcemia requiring calcium gluconate, calcium, and vitamin D supplementation, with good recovery . Patient B: A 14-year-old boy presented with abdominal pain, vomiting, and progressive bilateralgenu varus, with a past iliopsoas avulsion fracture. Investigations showed hypercalcemia with elevated PTH levels. Preoperatively , he was managed with hyperhydration, loop diuretics, zoledronic acid, and cinacalcet. Imaging revealed a left lower parathyroid adenoma. Duringsurgical excision, he developed intraoperative hypocalcemia, followed by postoperativeneuro muscular symptoms, requiring calcium, vitamin D, and magnesium supplementation. Conclusions: Paediatric PHPT is usually presented late with end-organ damage like our patients who had severe bone deformities. Prompt medical management with predication of postoperative hypocalcemia is needed before the definitive surgery . HBS is a life-threatening complication that we encountered in both patients. These patients require regularpostoperative monitoring of calcium and PTH for long periods due to asymptomatic hypocalcemia and to detect recurrences.