In 12 patients with secondary hyperparathyroidism, 13 parathyroid tumors detected with the use of sonography and confirmed by fine-needle aspiration biopsy were treated by percutaneous injection of absolute ethanol under ultrasonographic guidance. Indications for this procedure were recurrence of parathyroid tumors after previous subtotal surgery, high surgical risk, or refusal of surgery. Significant volume reductions were recorded for the larger glands; in the smaller ones, structural changes were observed as well. Clinical and biochemical therapeutic effects were obtained in most cases of single hyperplastic glands treated. Percutaneous alcoholic ablation of enlarged parathyroid glands can be used in cases of secondary hyperparathyroidism when surgery is contraindicated or problematic; it can also improve responsiveness to medical therapy, delaying the need for surgery.