In the United States, hepatitis C virus (HCV) diagnoses among reproductive-aged women are increasing amidst the ongoing opioid and drug overdose epidemic. While previous studies document racial and ethnic disparities in HCV testing and treatment in largely male populations, to our knowledge no national studies analyze these outcomes in reproductive-aged women with opioid use disorder (OUD). We analyzed data from a cohort of reproductive-aged women (aged 15-44 years) with diagnosed OUD captured in the TriNetX Research Network, a network of electronic health records from across the United States. Using a log-binomial model, we assessed differences in achieving HCV cascade of care stages (HCV antibody testing, HCV infection [positive HCV RNA test result], linkage to care, and HCV treatment) by race and ethnicity. From 2014 to 2022, 44.6% of the cohort were tested for HCV antibody. Asian and black/African American individuals had a lower probability of having an HCV antibody test than white individuals (risk ratio, 0.77 [95% confidence interval, .62-.96] and 0.76 [.63-.92], respectively). Among those with HCV infection, only 9.1% were treated with direct-acting antivirals. Hispanic/Latinx individuals had a higher probability of treatment than non-Hispanic/Latinx individuals (risk ratio, 1.63 [95% confidence interval, 1.01-2.61]). Few reproductive-aged women with OUD are tested or treated for HCV. Disparities by race and ethnicity in HCV testing further exacerbate the risk of perinatal transmission and disease progression among minoritized communities. Interventions are needed to improve overall rates of and equity in HCV screening and treatment for reproductive-aged women.