In order to evaluate the consequences of pituitary insufficiency on bone mineral status, bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry in 33 patients (aged 22-65 years) with pituitary insufficiency. BMD of the lumbar spine and femoral neck was decreased. Twenty of the patients were randomized to receive either recombinant human growth hormone (GH), 0.25 IU/kg/week for 6 months (0.125 IU/kg/week during the first month), or placebo. Serum osteocalcin levels increased significantly during GH administration. In the GH-treated group, there was no change in lumbar spine BMD and a small but significant decrease in femoral neck BMD (p < 0.05) after 6 months. Treatment periods longer than 6 months are needed to evaluate the potential beneficial effect of GH on BMD. This is in accordance with our previous findings of an increase in forearm BMD after 12 months of GH substitution therapy.