For many decades it has been known that there is a close relationship between renal disease, osseous changes, and "parathyroid hyperfunction," or hyperplasia of the parathyroid glands.1-4However, due to the apparent infrequency of clinically demonstrable bone disease, serious attention was not paid to this problem in the United States until the excellent British studies of Stanbury5and Dent et al6appeared. Although not conclusively demonstrated, it seemed that the incidence of renal osteodystrophy together with chronic renal failure was considerably greater in the British Isles than in the United States. It is probable that in the last years of World War II and early postwar period in England, the diet was somewhat deficient in calcium, phosphorus, and vitamin D (absence of fortified dairy products); in addition, the amount of sunlight and ultraviolet exposure is probably significantly less than in most areas of the United States. If