Patients suffering from chronic inflammatory conditions often take glucocorticoid medications over long periods of time. More than a million patients in the United States receive these agents each year. One of the most serious side effects of this treatment is glucocorticoid-induced osteoporosis (GIOP). This study characterized glucocorticoid use and osteoporosis screening and treatment patterns within a large U.S. health maintenance organization (HMO). This retrospective cohort study (n=3,031) used the HMO's electronic medical record and databases to identify patients who were dispensed the equivalent of >5 mg of prednisone per day for at least 90 days from January 2000 through December 2001. It assessed the primary outcomes, the percent who received a bone mineral density (BMD) measurement from January 1996 through 6 months after the index glucocorticoid prescription and the percent dispensed an osteoporosis medication within 6 months before or after the index glucocorticoid prescription. The participants' mean age was 61.4 years, 60% were women, and the mean daily dose of corticosteroids was 20.0 mg of prednisone equivalents. The most frequent diagnoses associated with glucocorticoid use were chronic obstructive pulmonary disease, 25.8%; asthma, 21.4%; rheumatoid arthritis, 17.2%. Overall, only 9.8% of the population received a BMD measurement--13% of women and 4.9% of men; 38% were dispensed osteoporosis medications--57.1% of women and 8.9% of men; only 14.5% received treatment with antiresorptive medications other than hormone replacement therapy--18.3% of women and 8.9% of men. Our study found that a substantial proportion of patients receiving long-term glucocorticoid therapy did not receive BMD measurement or preventive therapy for osteoporosis, as recommended in GIOP practice guidelines. Future research should focus on understanding barriers to GIOP identification and facilitating osteoporosis management.