Twenty-seven patients with parathyroid hyperplasia secondary to renal failure have had parathyroidectomy. Normally 3¾ of the parathyroid glands were removed. There were 12 women and 15 men with a mean age of 36.8 years and a median age of 34 years. Ten patients (37%) required some mediastinal dissection to locate and remove the lower parathyroid glands. Three patients (11%) required early reoperation for bleeding. Two patients had functioning renal transplants preoperatively and two had successful postoperative renal transplants. Ten of the patients (37%) had "adenomatous-like" masses within the hyperplastic glands. These should be designated as "adenomas" occurring in hyperplasia. The cooperative team approach of the surgeon and the pathologist is a vital factor in successful parathyroid surgery.