The Journal of Rheumatology Copyright © 2014. All rights reserved. Objective. Using administrative data from a large commercial US health insurer, we investigated temporal trends in medication use among children diagnosed with juvenile idiopathic arthritis (JIA). Methods. Children with ≥ 1 physician diagnosis code for JIA in the calendar years 2005 through 2012 were included. Use of tumor necrosis factor inhibitors (TNFi), methotrexate (MTX), nonsteroidal antiinflammatory drugs (NSAID), and oral glucocorticoids (GC) was determined. Temporal changes in medication usage were evaluated with the Cochran-Armitage test for trend. We used paired t-tests to evaluate the use of NSAID and GC in the 6 months before and after new TNFi use. Results. We identified 4261 unique individuals with JIA. The proportion of patients receiving TNFi increased from 8.7% in 2005 to 22.4% in 2012 (p < 0.0001). MTX use increased from 18.4% to 23.2% (p = 0.02). NSAID use decreased from 49% to 40% (p = 0.02). GC use was relatively unchanged. Following new TNFi use, the mean number of NSAID prescriptions (among prevalent users) decreased from 2.8 to 2.0 (p < 0.0001), and the mean daily GC dose (among prevalent users) decreased from 7.3 mg/day to 3.9 mg/day (p < 0.0001). Many new TNFi users (57%) had not used MTX in the previous 6 months, and only 37% had any concurrent MTX use in the 6 months following new TNFi use. Conclusion. TNFi use in the treatment of JIA increased 2- to 3-fold over the last 8 years. New TNFi use was associated with decreased NSAID and GC use. TNFi may be replacing, rather than complementing, MTX in the treatment of many patients.