This study examines the impact of a prescription duration limit policy tailored to different clinical settings on opioid prescribing patterns among Medicaid enrollees in West Virginia. The policy, implemented in June 2018, imposed specific limits on opioid prescriptions: 7 days for adults in outpatient hospital or office-based settings, 4 days for adults in emergency departments, and 3 days for pediatric patients. The study analyzed data from January 1, 2017, to September 30, 2019, and found that the policy was associated with significant reductions in the proportion of prescriptions exceeding the limits. Specifically, it led to a 56.8% relative reduction in prescriptions exceeding the 7-day limit for adults in outpatient settings, a 37.5% relative reduction for adults in emergency departments, and a 26.5% relative reduction for pediatric patients. The findings suggest that policies tailored to specific clinical settings may effectively reduce opioid prescription lengths, but further research is needed to evaluate potential unintended consequences, such as shifts to illicit opioids.This study examines the impact of a prescription duration limit policy tailored to different clinical settings on opioid prescribing patterns among Medicaid enrollees in West Virginia. The policy, implemented in June 2018, imposed specific limits on opioid prescriptions: 7 days for adults in outpatient hospital or office-based settings, 4 days for adults in emergency departments, and 3 days for pediatric patients. The study analyzed data from January 1, 2017, to September 30, 2019, and found that the policy was associated with significant reductions in the proportion of prescriptions exceeding the limits. Specifically, it led to a 56.8% relative reduction in prescriptions exceeding the 7-day limit for adults in outpatient settings, a 37.5% relative reduction for adults in emergency departments, and a 26.5% relative reduction for pediatric patients. The findings suggest that policies tailored to specific clinical settings may effectively reduce opioid prescription lengths, but further research is needed to evaluate potential unintended consequences, such as shifts to illicit opioids.