The purpose of this study was to evaluate the impact of opioid-limiting legislation on perioperative opioid prescriptions in total knee arthroplasty. The hypothesis was that opioid legislation has reduced opioid prescription filling above levels anticipated by national trends. This study retrospectively evaluated opioid prescription filling for all patients undergoing total knee arthroplasty in a commercially available insurance database between 2010 and 2018 (n=1,068,764). Initial discharge and 90-day cumulative oxycodone 5-mg equivalents filled were tabulated. Opioid prescription filling was evaluated over time and between states with and without opioid-limiting legislation using analysis of variance and multivariable linear and logistic regression. States with and without opioid legislation had significant reductions in initial and cumulative opioid prescription filling volume (all P<.001). However, the magnitude of this reduction was larger in states with opioid legislation. Legislation targeting duration and volume had the largest impact on initial post-act opioid prescription filling volume compared with states without legislation in an estimated "pre-act" time frame. Legislation targeting duration and volume and no specific target had the largest impact on cumulative post-act opioid prescription filling volume. States without legislation still had large, significant reductions in filling volume, but the magnitude was not as great as in states with opioid legislation. States with and without opioid legislation had significant decreases in initial and cumulative opioid prescription filling volume. However, the magnitude of reduction was larger in states that enacted legislation. Younger age, pre-operative opioid use, and higher comorbidity burden were associated with greater opioid use postoperatively. [Orthopedics. 2023;46(3):142-150.].