Summary: We applied regression techniques to a large cohort of patients to understand why certain patients are prescribed medications to prevent glucocorticoid-induced osteoporosis (GIO). Rates of prescriptions to prevent osteoporosis were low. The presence of drugs and disorders associated with osteoporosis and gastrointestinal conditions actually are associated with a decreased likelihood of receiving osteoporosis-preventing medications. Introduction: To understand why some patients are prescribed medications to prevent GIO while other patients are not, we examined whether there is an association among osteoporosis-inducing medical conditions or medications and prescriptions for osteoporosis prophylaxis in a large cohort of rheumatoid arthritis patients on chronic glucocorticoids. Methods: Department of Veterans' Affairs national administrative databases were used to construct a cohort (n = 9,605) and provide the data for this study. Multivariate logistic regression was performed to determine medical conditions and medications associated with dispensing of GIO-preventive medications, controlling for sociodemographic variables, comorbidities, glucocorticoid dosage, prior fractures, and rheumatoid arthritis severity. A subanalysis examined predictors of early GIO prevention. Results: Subjects were more likely to receive GIO prophylaxis if they were older, African American, treated with multiple antirheumatic disease-modifying drugs, or received greater glucocorticoid exposure. The prescription of certain drug classes (loop diuretics and anticonvulsants) and conditions (malignancy, renal insufficiency, alcohol abuse, and hepatic disease) were associated with lower likelihood of GIO prophylaxis, despite putative links between these agents/conditions and osteoporosis. The presence of gastrointestinal disorders dramatically decreased likelihood of GIO prophylaxis. Few characteristics predicted the dispensing of GIO-preventing medications within 7 days of the initial glucocorticoid start date. Conclusions: Rates of prescriptions to prevent osteoporosis in a cohort of older men with rheumatoid arthritis on chronic glucocorticoids were low. Gastrointestinal disorders and drugs and disorders potentially linked to osteoporosis are associated with diminished odds of being prescribed GIO-preventing medications. © 2010 International Osteoporosis Foundation and National Osteoporosis Foundation.