Bone histology was examined in 32 patients with chronic cholestatic liver disease, of whom just over one half were receiving high-dose parenteral vitamin D therapy. Four patients had histological evidence of osteomalacia; two of these were receiving vitamin D therapy, and showed only very mild osteomalacia, while the remaining two untreated patients had more severe bone disease. Plasma 25-hydroxyvitamin D levels were normal in all vitamin D-treated patients, and serum calcium concentrations were significantly higher in the treated group. Clinical symptoms and biochemical and radiological findings were unreliable in predicting osteomalacia. It is concluded that osteomalacia is uncommon in patients with chronic cholestatic liver disease irrespective of whether or not they are receiving vitamin D therapy. However, high-dose parenteral vitamin D prophylaxis protects against vitamin D deficiency and may also prevent the development of severe bone disease.