We retrospectively reviewed the presentation and management of children with primary hyperparathyroidism (PHPT) from 1973 to 1995 at a paediatric tertiary-care centre. There were 11 patients (6 females), aged 12.3-17.7 years at presentation, with sporadic PHPT confirmed by histopathology (single adenoma). Presentation consisted of renal colic, or non-specific gastrointestinal, musculoskeletal or neurological symptoms. Misdiagnosis was common until hypercalcaemia was identified, 0.5-24 months after onset of symptoms (mean 7.7 months). All patients had hypercalcaemia and low-normal serum phosphate. The parathyroid hormone (PTH) radioimmunoassay used before 1986 was elevated in 1/4 patients; the intact PTH assay used after 1986 was elevated in 7/7 patients. At presentation, six had end-organ damage: band keratopathy, renal lesions, and/or bone disease. Preoperative localization was accurate in 0/4 patients diagnosed before 1986, but 5/7 patients diagnosed after 1986: three by ultrasound or sestamibi scan alone, and two by ultrasound and technetium scan. Surgical outcome was not dependent upon the accuracy of pre-operative localization. PHPT is rare in children but usually associated with end-organ damage, presumably due to delayed diagnosis. It should be considered in the differential diagnosis of unexplained non-specific complaints. The intact PTH assay greatly assists pre-operative diagnosis. The usefulness of pre-operative localization requires further research.