Primary hyperparathyroidism is a rare disease in children. We present the case of a 10 month old child who had a neonatal form of this disease. The first diagnosis considered in this patient was rickets, because of the clinical and radiological signs. Serum calcium was at the upper limit of normal [2, 7 mmol/L]. The radiological control after 3 weeks of treatment with vitamine D and calcium showed the absence of the metaphyseal dense line but there was a hypercalcemia at 3, 7 mmol/L [14, 8 mg/ dL], reaching afterwards 7, 2 mmol/L [28, 8 mg/dL]. The diagnosis of a neonatal form of primary hyperparathyroidism was considered and confirmed with a parathormone level at 370 pg/ml [normal < 60 pg/ml.25 OH D3 level was 60 mg/ml [normal: 20-80 mg/ml]. Surgery found 4 hyperplastic parathyroid glands, and the pathological diagnosis was principal cell hyperplasia. The evolution after subtotal parathyroidectomy was maked by clinical and biological hypocalcemia that responded well to the treatment with alfacalcidiol and calcium. Clinically, tonus was much improved and the child walked at 21/2 years [1 year after surgery]