OBJECTIVES: To determine the real-world, one-year cost of RA treatment for patients initiating therapy with an infused biologic from a US commercial payer perspective. METHODS: We conducted a retrospective, administrative claims-based analysis of RA patients enrolled in a large U.S. managed care plan who initiated an infused RA biologic (infliximab, abatacept, rituximab) between January 2, 2006 to January 31, 2009.   Patients ≥18 years of age, with ≥1 diagnosis of RA and continuously enrolled in the health plan 6 months prior to and ≥12 months following treatment initiation, were included.  Patients with diagnoses of non-RA conditions for which the study drugs are used were excluded. We assumed that rituximab and abatacept patients had received ≥1 anti-TNF agent, and only included infliximab patients who had evidence of a prior anti-TNF agent. Generalized linear models with a log link and gamma distribution were employed to compare Total RA-related costs (RA medication+healthcare services with diagnosis of RA), RA medication costs (biologics, other DMARDs, NSAIDs, corticosteroids) and Index biologic costs (drug+administration), among patients treated with each  infused biologic, while controlling for demographics, co-morbidity score, plan type, index year, and prior RA medications (methotrexate, NSAIDS, corticosteroids). RESULTS: A total of 813 patients met the inclusion criteria (n=156 infliximab, n=418 abatacept, n=239 rituximab), 82% women, average age 52 years (SD=11.7).  During the one-year following treatment initiation adjusted costs were as follows: Total RA-related health care costs (Rituximab = $26,783; Abatacept = $24,344; Infliximab = $27,053; p=0.1249), RA medication costs (Rituximab = $19,973; Abatacept = $19,000; Infliximab = $20,763; p=0.1840), and Index biologic costs (Rituximab = $17,638; Abatacept = $16,233; Infliximab = $17,845; p=0.1256). CONCLUSIONS: We did not find a difference in one-year RA-medication costs or total RA-related costs between patients starting rituximab, abatacept, or infliximab. From a U.S. commercial payer perspective the costs associated with the three infused RA-biologics are similar.