In recent years the role of the parathyroid gland in relation to certain diseases of the bones has assumed considerable proportions. This subject is of extreme importance to the roentgenologist because of the bony changes observed by the X-ray. In 1904, Askanazy (1) first reported a case of generalized osteitis fibrosa, described by von Recklinghausen (2) in 1891, associated with a parathyroid tumor. In 1907, Erdheim (3) described three cases of osteomalacia in which there was hypertrophy or tumor formation of the parathyroids. This raised a question as to whether the hyperplastic condition of the parathyroid was primary and the skeletal changes secondary or vice versa. Erdheim contended that the enlarged glands were a compensatory change due to the increased drain of calcium metabolism resulting from the bony condition. As late as 1926, Kerl (4) in describing a case of osteomalacia and osteoporosis, believed this possibility. However, most authorities are of the opinion that the enlarged parathyroid is t...