OBJECTIVE To determine the effects of short-term glucocorticoid administration in healthy elderly men on bone GLA protein (BGP) levels, as well as levels of calcium, phosphorus, immunoreactive parathyroid hormone (PTH), and alkaline phosphatase. METHODS Subjects served as own control before and after prednisone treatment. METHODS Male subjects were recruited by telephone from the Duke University Aging Center Volunteer Registry and the Department of Veterans Affairs Medical Center Gerofit Program (a supervised exercise program). METHODS Healthy males age greater than 60 years with no history of diabetes mellitus, glucose intolerance, or prior glucocorticoid use. Subjects could not be taking diuretic agents and could not have osteoporosis. The seven subjects mean age +/- std dev was 68.6 +/- 5.3 years. METHODS Prednisone 40 mg orally for 5 days. Fasting serum was obtained at baseline, on days 7 through 11, 13, 15, and 17. Assays of BGP, calcium, phosphorus, PTH, and alkaline phosphatase were performed. METHODS Changes in serum BGP levels was the primary outcome measure. Changes in serum calcium, phosphorus, PTH, and alkaline phosphatase levels were secondary outcome measures. RESULTS Treatment caused reduction in BGP levels within 24 hours of first dose of prednisone, with levels dropping an average of 78% during the 5 days of treatment (P = 0.004). Within 24 hours of stopping treatment, BGP was no different from baseline. Other variables did not change with treatment. CONCLUSIONS Glucocorticoid treatment suppresses BGP production in healthy elderly men in the same fashion as it does in younger healthy men.