OBJECTIVES: Opioid-related deaths and overdoses have paralleled increases in opioid prescribing, however the influence of health payers on opioid prescribing is unclear. Under the Affordable Care Act, Arkansas expanded coverage to poor and near poor by enrolling persons into qualified health plans (QHPs) or Medicaid based on frailty level and income. This study sought to compare opioid use, chronic opioid use, and geographic variability in opioid use between individuals enrolled in Medicaid and QHPs. METHODS: Administrative claims data of newly enrolled subjects with at least six months of continuous coverage in 2014 were analyzed. Chronic use was defined as having at least ten opioid prescriptions over a minimum period of 90-days. A regression discontinuity design using a frailty-score which assigned subjects to Medicaid or QHPs was used to estimate the plan effect on opioid use and chronic opioid use. RESULTS: The final sample comprised of 151,429 individuals with a mean age of 39.78 years, 59.07% females, and 24.69% and 4.64% had a mental health and substance use disorder. There were 21,899 persons enrolled in FFS Medicaid and 129,530 in QHPs. Rates of opioid use among Medicaid and QHPs were 50.11% (49.44% - 50.77%) and 38.96% (38.69% - 39.22%) respectively. Chronic use rates among opioid user for Medicaid and QHPs were 19.97% (19.22% - 20.72%) and 13.25% (12.96% - 13.55%) respectively. Any opioid use was highest in the South-Central region (44.96%) and lowest in the North-West (36.19%). The regression discontinuity model showed that any opioid use (OR = 0.905, p=0.128) and chronic opioid use (OR = 0.973, p=0.891) did not differ between QHPs and Medicaid. CONCLUSIONS: Overall, high rates of opioid use and chronic use were found, which did not differ by Medicaid or QHP enrollment. Opioid use and chronic use only showed modest variability across geographic regions in the state.