ObjectiveThis is a quality improvement project to determine the best process to identify and address gaps in care for perinatal patients in receiving appropriate hepatitis C virus (HCV) testing and treatment across the largest health system in Maine.Study DesignWe reviewed electronic medical record data between October 1, 2015, and February 1, 2020, to investigate rates of HCV testing and treatment among 916 perinatal patients with opioid use disorder across 8 hospitals using a “cascade of care” framework, a model used previously to identify gaps in care and treatment of chronic diseases.Main Outcome MeasureWe examined HCV testing and treatment rates along the cascade of care and patient characteristics associated with HCV antibody testing and treatment, separately, using log binomial regression models. Models were adjusted for age, residential distance to medical center, psychiatric diagnosis, and opioid agonist therapy at delivery.ResultsOf pregnant patients eligible for screening, 64% (582/916) received HCV antibody testing. Of 136 patients with active HCV infection, 32% (n = 43) received a referral for treatment, 21% (n = 28) were treated, and 13% (n = 18) achieved sustained virologic response. In the adjusted regression models, only opioid agonist therapy was associated with HCV antibody testing (adjusted risk ratio, 1.31; 95% confidence interval, 1.18–1.46), and no factors were significantly associated with receipt of treatment among HCV viremic patients.ConclusionLow referral and treatment rates signify the need for quality improvement interventions to improve coordination of care between multiple disciplines and practice settings to increase access to HCV treatment.