OBJECTIVE: To characterize glucocorticoid use and patterns of osteoporosis prevention therapies among a large US national cohort. METHODS: Health maintenance organization (HMO) members who were receiving chronic glucocorticoid therapy (> 90 day supply) within a 3 year observation period were identified along with their prescribing physicians. Receipt of anti-osteoporotic prescription therapies and bone mass measurement was determined. Multivariable analyses were used to define significant predictors of these preventive interventions. RESULTS: We identified 2378 HMO members who filled prescriptions for at least a 90 day supply of glucocorticoids, but had not filled a glucocorticoid prescription in the prior 90 days. In women over age 50, use of anti-osteoporotic therapies and bone mass measurement was 41% and 16%, respectively. Glucocorticoid-prescribing physicians were identified for 878 (37%) of these glucocorticoid users, and internal medicine specialists (39%) and rheumatologists (20%) wrote the majority of the prescriptions for glucocorticoids. Women age 50 and over were most likely to receive a prescription anti-osteoporotic preventive therapy (OR 4.0; 95% CI 1.5-10.8). Patients with a rheumatologist prescribing their glucocorticoids were more likely than those of internists to have a bone mass measurement (OR 2.2; 95% CI 1.3-3.6) and receive bisphosphonates (OR 1.9; 95% CI 1.1-3.1), but were not more likely to receive preventive treatment overall. CONCLUSION: Although better than in several prior studies, we identified low levels of selected preventive care measures for chronic glucocorticoid users in a large population based cohort. Significant demographic and practice pattern variation suggests opportunities for targeted preventive interventions.