Policies that address opioid dose limits may help to decrease high-risk opioid prescribing. We evaluated 3 sequential and progressive decreases in high-dose (HD) opioid limits implemented by Massachusetts Medicaid over 15 years. The study population included members ages 18 to 64 years with > /=1 claim for a schedule II opioid between January 2002 and March 2017. The 3 interventions consisted of prior authorization requirements for prescriptions exceeding the morphine equivalent dose (MED) HD dose limits: > 360 mg (intervention 1a and 1b), > 240 mg (intervention 2), and > 120 mg (intervention 3). A segmented regression evaluated the change in natural log of the average daily MED (AD_MED). The natural log of the AD_MED decreased during the 6 quarters after intervention 1a (P < .001), immediately after intervention 1b (P=.0002), and continued to decrease over the following 8 quarters (P=.023). The natural log of the AD_MED decreased immediately after intervention 2 (P=.002) and again after intervention 3 (P < .001). The percentage of users exceeding the HD limits of 360 mg, 240 mg, and 120 mg MED decreased by 87.3%, 79.8%, and 75.2% from baseline, respectively. The natural log of the AD_MED decreased among members after implementation of 3 sequential and progressive HD prior authorization limits, as did the percentage of members exceeding each of the HD limits. PERSPECTIVE: This study demonstrates the longitudinal impact of a prior authorization policy-based HD limit in a Medicaid population. This study contributes to options for policymakers and other Medicaid programs as a potential strategy to assist in addressing the opioid epidemic.