The frequency with which primary surgical lesions of the parathyroid gland are diagnosed clinically has steadily increased within the past 10 years. The commonest disease is hyperparathyroidism, which may be produced by primary tumors of this gland or by diffuse hyperplasia. The commonest tumor involving the parathyroid is benign adenoma; carcinoma is quite rare. In fact, Cope5 reported that he and his associates had removed 91 benign parathyroid adenomas before they encountered their first patient with carcinoma. The problem of the diagnosis of carcinoma of the parathyroid gland has been discussed by many authors, and opinions vary concerning the criteria necessary for this diagnosis.1,3,5,7,9 Thus, as late as 1953 von Albertini1 stated that the term "benign, metastasizing adenoma" was justified. This opinion is the exception, however, for other authors writing on the subject concede that those tumors which metastasize are truly carcinoma. It is also generally conceded