OBJECTIVES: FDA prescribing information for infliximab (IFX) treatment of patients with rheumatoid arthritis (RA) recommends infusions at weeks 0, 2 and 6 followed by every 8 weeks, with a 4 week option.  This study examines infusion intervals in RA patients enrolled in a large United States health plan. METHODS: Claims data were obtained from the i3Innovus database for October 2006 through June 2009.  Inclusion criteria were ≥ 2 diagnoses for RA (714.xx), absence of a diagnosis for selected anti-inflammatory disorders, age ≥18, ≥4 IFX infusions, absence of any biologic claim for 6 months prior to index date, and ≥ 12 months of continuous eligibility post-index.  A treatment episode was defined as infusions from index claim to the last IFX claim in the dataset without a claim for other biologics during that episode. Patients with IFX infusions ≥ 180 days were excluded. The sample mean at each infusion was compared to prescribing information. RESULTS: Of patients meeting inclusion criteria (N=652), the number of infusions received ranged from 4 to 48 (mean of 11).  The mean interval (±SD) between the first and second infusion was 20 days (±17); 76% of the sample received their infusion within three days of the recommended 14 days.  The mean interval between the second and third infusion was 33 days (±12).  The mean interval between each of the next 8 maintenance infusions ranged between 50 and 54 days (SDs ranging from 15-16 days), with a mean across all intervals of 51 days (7+ weeks). CONCLUSIONS: Data from this national health plan indicate that induction and maintenance intervals were consistent with the FDA recommended prescribing information.  Physicians in this particular health plan appeared to be administering IFX in accordance with the FDA-approved administration schedule for RA.