BACKGROUND: Glucocorticoids are recommended for short-term use in rheumatoid arthritis (RA), but many patients remain on long-term therapy. We evaluated the variability in glucocorticoid prescribing across rheumatologists to inform interventions to limit long-term glucocorticoid use to the lowest dose necessary. METHODS: Two cohorts were created using Medicare data 2006-2015. Using cohort 1 (RA patients on DMARDs), we calculated each rheumatologist's "provider preference" for glucocorticoids (frequency of use compared to other providers), using ratio of observed to expected number of patients receiving glucocorticoids to account for case-mix. In cohort 2 (RA patients on stable DMARD therapy) we evaluated whether provider preference for glucocorticoids could independently predict use of ≥5mg/day of glucocorticoids 6-9 months after DMARD initiation. RESULTS: Using Cohort 1 (1,272,644 yearly observations, 385,597 patients) we calculated provider preference among 6,875 rheumatologists (28,936 yearly observations). Provider preference was highly variable, with physicians at the lowest and upper quartiles using glucocorticoids 33% less often (25th percentile) to 31% more often (75th percentile) than expected. In Cohort 2 (155,539 patients on stable DMARD therapy), provider preference was strongly associated with glucocorticoid use ≥5mg/day at 6-9 months, with predicted probability of use 22% (95% CI 21.7-22.7) vs. 11% (10.2-10.9) for a patient seeing a provider in the highest versus lowest quintile of preference. CONCLUSION: Glucocorticoid prescribing for RA varies greatly among rheumatologists; provider preference is one of the strongest predictors of a patient's long-term glucocorticoid use. These results raise quality of care concerns and highlight the need for stronger evidence to guide RA treatment.