BACKGROUND: Current therapeutic options for Gaucher disease type 1 (GD1) include intravenous enzyme replacement therapy (ERT) with imiglucerase, velaglucerase alfa, or taliglucerase alfa or oral substrate reduction therapy (SRT) with eliglustat or miglustat. Transfer of patients from ERT to SRT may present an opportunity for cost savings. OBJECTIVES:  This study evaluated the budget impact associated with increased utilization of eliglustat for the treatment of adults with GD1. METHODS:  A budget impact model reflecting the US payer perspective calculated the change in pharmaceutical and administration costs resulting from increasing eliglustat market share from 12% (current) to 44% (hypothetical). Eliglustat market share was drawn equally from existing shares of imiglucerase (40%) and velaglucerase alfa (40%) and assumed to be static over the analysis period. Unit costs were obtained from Redbook (WAC), 2016. ERT WAC costs were adjusted to account for site of care-based markup and the proportion of patients receiving infusions in each site of care based on a typical large regional health plan. Administration costs were obtained from analysis of claims (DataMart Multiplan). All costs expressed in 2016 USD. RESULTS:  In a plan with 5 million members and 25 treated patients with GD1, increased utilization of eliglustat, shifting market share evenly from all sites of care, resulted in total 3-year savings of $4.58M (13.6%) to the plan. The corresponding per member per month (PMPM) savings were $0.025. When all patients receiving ERT infusions in the hospital outpatient setting were shifted to eliglustat, 3-year savings increased to $7.75M (23.0%) and PMPM savings increased to $0.043. Results were sensitive to proportion of patients receiving infusions at each site of care. CONCLUSIONS:  Based on these analyses, increased utilization of eliglustat resulted in meaningful cost savings to a payer’s overall budget. Cost savings are highest among patients switching from ERT administered in a hospital outpatient setting.