Abstract Metabolic bone disease is most often diagnosed by a combination of radiological features, clinical signs and symptoms and biochemistry for serum calcium, phosphate and alkaline phosphatase. The most common metabolic bone disease is osteoporosis which affects elderly patients, particularly women and is a disease on the increase in the Western world. It is now recognized that osteoporosis can be of a ‘high-turnover' type or a ‘low-turnover' type and a bone biopsy is often the only way to definitely establish which kind of osteoporosis is present. The rest of the metabolic conditions are relatively rare and again are often diagnosed without resorting to biopsy. Patients with renal osteodystrophy may still benefit from having a bone biopsy examined by undecalcified sections with tetracycline labelling to establish the contribution of osteomalacia and hyperparathyroidism to their symptoms. The measurement of circulating parathormone has obviated the need for a biopsy in most patients with hyperpara-thyroidism. Occasionally, a biopsy is necessary to establish a diagnosis of osteomalacia and a cause of the osteomalacia can occasionally be demonstrated in such a biopsy. Paget's disease of bone is included in the metabolic bone disease conditions although strictly speaking it is not a generalized bone condition and therefore iliac crest biopsies are not employed in the diagnosis of Paget's disease; rather the bone affected is biopsied. Nevertheless, the histopathology of Paget's disease can mimic osteomalacia and hyperparathyroidism.