IMPORTANCE Early pregnancy loss (EPL) is the most common complication of pregnancy. A multicenter randomized clinical trial compared 2 strategies for medical management and found that mifepristone pretreatment is 25% more effective than the standard of care, misoprostol alone. The cost of mifepristone may be a barrier to implementation of the regimen. OBJECTIVE To assess the cost-effectiveness of medical management of EPL with mifepristone pretreatment plus misoprostol vs misoprostol alone in the United States. DESIGN, SETTING, AND PARTICIPANTS This preplanned. prospective economic evaluation was performed concurrently with a randomized clinical trial in 3 US sites from May 1, 2014, through April 30, 2017. Participants included 300 women with anembryonic gestation or embryonic or fetal demise. Cost-effectiveness was computed from the health care sector and societal perspectives, with a 30-day time horizon. Data were analyzed from July 1, 2018, to July 3, 2019. INTERVENTIONS Mifepristone pretreatment plus misoprostol administration vs misoprostol alone. MAIN OUTCOMES AND MEASURES Costs in 2018 US dollars, effectiveness in quality-adjusted lifeyears (QALYs), and treatment efficacy. Incremental cost-effectiveness ratios (ICERs) of mifepristone and misoprostol vs misoprostol alone were calculated, and cost-effectiveness acceptability curves were generated. RESULTS Among the 300 women included in the randomized clinical trial (mean [SD] age, 30.4