Familial hypocalcuric hypercalcemia is a condition that is often incorrectly diagnosed and treated. We studied a family with seven members who had familial hypocalcuric hypercalcemia. In four of the family members it was difficult to make the diagnosis. A correct diagnosis was made in the other three on the basis of known family history. Subtotal parathyroidectomi was carried out on three of the family. After operation, two of these experienced a relapse, and one became permanently hypocalcemic.