OBJECTIVES: 1) To investigate racial disparities in medication use in Rheumatoid Arthritis (RA) patients; 2) To identify factors associated with using a biologic tumor necrosis factor inhibitor (biologic-TNF). METHODS: We identified patients 18-64 years old with at least two diagnoses of RA and one prescription fill for Disease-Modifying Anti-Rheumatic Drugs (DMARDs) within the first year of diagnosis from the California Medicaid (Medi-Cal) claims data (1995-2006). The annual prevalence of medication use for each racial group was calculated. A generalized linear model was used to assess for predictors of annual biologic-TNF use during 1999-2006. RESULTS: We analyzed 6,463 patients. The biologic-TNF use increased from 7.0%, 6.5%, 2.5% in 1999 to 22.9%, 24.5%, and 14.3% in 2006; but the DMARD use decreased from 80.7%, 82.3%, 76.8% in 1995 to 71.9%, 72.4%, and 71.4% in 1999 for Whites, Hispanics, and Blacks, respectively (all p<0.0001). The difference in prevalence of biologic-TNF use between Whites and Blacks ranged from 4.5% in 1999 to 11.0% in 2005. The DMARD use among racial groups was not different during 1995-2000 (pre-biologic) (all p>0.05). Hispanics (75.3% to 81.0%) were more likely to use DMARDs than Whites (74.0% to 70.1%) or Blacks (64.0%) to 66.5%) from 2001 to 2006 (all p<0.001). The differences in prevalence of DMARD use between Whites and Blacks were largest (12.4%) in 2002, but decreased to 3.6% in 2006 (all p<0.001). Significant predictors of biologic-TNF use included Blacks [Odd ratio (OR)=0.48], Hispanics (OR=0.68) as compared to Whites, Medi-Cal and Medicare dual eligibility (OR=1.34), not filling DMARD (OR=0.34),  greater number of RA medication fills (OR=2.12), fewer comorbidities (OR=0.88), and access to a Rheumatologist (OR=1.01). CONCLUSIONS:  Biologic-TNF and DMARDs were used disproportionately in Blacks and Hispanics across 1999 to 2006. In addition to race, clinical/treatment factors, comorbidity, and Medicare eligibility have significant impact on utilization of biologic-TNF.