During long-term dialysis of patients in chronic renal failure disorders of mineral metabolism in the sense of renal osteodystrophy occur increasingly with time. Quite separate from these patients with renal osteopathy (osteomalacia and osteopenia) as a result of dialysis there is a group of patients in whom, despite appropriate dialysate composition, a full-blown picture of renal osteodystrophy due to secondary hyperparathyroidism develops. Subtotal parathyroidectomy will significantly improve them. Experience in 12 patients has demonstrated that, in addition to the clinical signs, biochemical findings and radiological changes, the quantitative evaluation of iliac crest biopsy and determination of parathormone and ionised serum-calcium fraction are decisive as indications for surgery. In these patients subtotal parathyroidectomy gave satisfactory results, but the treatment of renal osteopathy in the sense of osteopenia is often unsatisfactory and the full clinical picture can often be improved only by early renal transplantation.