Abstract
The histological findings in 18 cases of parathyroid hyperplasia associated with chronic renal failure and haemodialysis have been compared with a series of 35 cases of primary adenomatous hyperparathyroidism. Analysis of several features suggests that there are no definite criteria for distinguishing microscopically between individual enlarged glands in primary and secondary hyperparathyroidism, although nuclear pleomorphism is more common in primary adenoma and nodules are more common in secondary hyperplasia. These findings are discussed.