OBJECTIVES: Management of hemophilia B includes replacement of factor IX (FIX) by intravenous infusion. The recent introduction of an extended half-life (EHL) FIX product enabled comparison of health care costs and factor utilization for hemophilia B patients who switched from a standard half-life (SHL) to EHL FIX product. METHODS: The Truven MarketScan US claims database (January 2010–July 2016) was used to compute health care utilization costs for patients with claims data for ≥3 months prior to and after switching from SHL to EHL product. Total health care costs included FIX replacement cost (drug cost) as well as hemophilia-related inpatient and outpatient costs. Data were analyzed 12 months before and after switching FIX products. RESULTS: Fourteen patients with hemophilia B in Truven database switched to EHL product. Total health care utilization costs were uniformly higher in the EHL phase (post-switch) in each of the corresponding 3-month time periods examined before and after the switch. Factor replacement accounted for 96%–100% of quarterly total health care utilization costs. Median quarterly total health care costs were $51,881, $80,589, $89,389, $56,076 (SHL), and $205,845, $185,988, $147,514, $175,667 (EHL), while median quarterly factor costs were $51,881, $77,523, $89,389, $55,726 (SHL), and $205,724, $183,451, $147,363, $173,515 (EHL) in the 12–10 (n=9), 9–7 (n=10), 6–4 (n=12), 3–1 and 1–3, 4–6 (n=12), 7–9 (n=8), and 10–12 (n=7) months pre- and post-switch, respectively. Median quarterly FIX IUs were 39,000, 58,465, 68,790, 43,310 (SHL), and 74,056, 64,111, 53,083, 43276 (EHL), respectively, in these periods. CONCLUSIONS: This real-world data analysis showed switching from SHL to EHL product was associated with more variable and higher health care costs in the US. Factor cost was the biggest driver of total health care costs. Further real-world analyses incorporating larger numbers of patients should be explored.