1. Iliac bone biopsies were obtained from nine patients 3 months to 6 years after bilateral nephrectomy. 2. In eight of the nine patients no histological evidence of vitamin D abnormality was seen in the bones after bilateral nephrectomy. 3. One patient showed histological evidence of osteomalacia before bilateral nephrectomy which improved but did not disappear after bilateral nephrectomy. 4. The biospies of all nine patients showed evidence of hyperparathyroidism. 5. It is concluded that normal bone mineralization can take place in the absence of the kidneys.