OBJECTIVES: Prescription opioid misuse has increased markedly and is associated with greater medical spending and decreased productivity. Given the association between high daily dose of prescription opioids and negative health outcomes, state workers’ compensation boards have implemented policies to reduce the morphine equivalent daily dose (MEDD) prescribed. The study objective is to evaluate the impact of MEDD guidelines among workers’ compensation claimants. METHODS: Claims data from a large, national workers’ compensation insurer were utilized. The treatment group consisted of injured workers from three states with workers’ compensation board guidelines implemented in 2012 recommending against prescriptions >120 mg MEDD—Massachusetts, which developed its own guideline, and California and Utah, which adopted their guidelines from the American College of Occupational and Environmental Medicine (ACOEM). Three comparison states—Illinois, Indiana, and Pennsylvania—were selected based on having similar policy landscapes and opioid utilization trajectories, but no MEDD policy during the study period. Multivariate regression analyses used average mg MEDD post-policy implementation as the outcome. Covariates included demographics, employment status, state fixed effects, and average MEDD pre-policy implementation. Policy indicators and interaction terms between policy indicators and high dose use (>120 mg MEDD) pre-policy were also included. RESULTS: Among