The calcium, vitamin D, and osteocalcin concentrations were investigated in 17 patients with anorexia nervosa. Serum 25-hydroxyvitamin D (25 OHD) concentrations below normal were observed in 15 (88%); only two patients has serum 1,25 dihydroxycholecalciferol (1,25(OH)2D) concentrations below normal. Serum parathyroid hormone (PTH) concentration was also normal in all except these two patients. Serum osteocalcin concentration was below normal in seven of 14 patients. Although a low concentration of serum 25 OHD is common in patients with anorexia nervosa in the United Kingdom, 1,25(OH)2D concentrations are usually normal. Hypovitaminosis D with secondary hyperparathyroidism is relatively uncommon. The subnormal osteocalcin concentrations observed in these patients probably reflect diminished osteoblastic activity, which may contribute to their osteopenia.