Ectopic parathormone production has become a well described entity. The availability of an assay for parathormone has enabled the tumors responsible for this syndrome to be more readily identified. The differential diagnosis must include primary hyperparathyroidism and, if this cannot be ruled out, neck exploration should be undertaken. If possible, the treatment for the ectopic parathormone syndrome should be the excision of the tumor. This is usually unsuccessful and treatment should be directed at the hypercalcemia. Temporary control is usually successful but recurrent hypercalcemia with its complications is ultimately fatal for the patient. Newer methods of treatment of these often slow-growing tumors may result in longer survival in many of these patients.