Abstract. Total parathyroidectomy is required to cure neonatal primary hyperparathyroidism (NPH) as any parathyroid remnant quickly becomes hyperplastic, causing recurrent hypercalcaemia. We present a patient with NPH who had total removal of his eutopic parathyroid glands but continued to have parathyroid hormone secretion from presumed ectopic parathyroid tissue. Hypercalcaemia initially recurred but normal calcium homeostasis was established as the child grew older. We postulate that the underlying defect in NPH is decreased sensitivity to the serum ionic calcium feedback inhibition at the parathyroid receptor level and that this sensitivity can improve with age.