622 patients were operated on between 1966 and 1988. Urolithiasis was the most common presenting symptom (26%) but routine measurements of serum calcium led to detect 50% cases. At present, the disease is three times more frequent in women than in men. Estrogenic deprivation, neck irradiation (3.4%) and lithium therapy favor the occurrence of hyperparathyroidism (HPT); frequent association with goiter (19.8%), diabetes (8.3%) and multiple endocrine neoplasia (3.5%) has been noticed. Bone Gla protein concentrations correlate with calcium and HPT blood concentrations but do not reflect the severity of bone damage. Dual photon absorptiometry is now available for quantification and follow-up of bone demineralization, especially in asymptomatic forms of HPT.