Introduction: Uptake of Proprotein Convertase Subtilisin/Kexin type 9 inhibitors (PCSK9i) among Medicare beneficiaries was initially slow because of coverage restrictions and high out-of-pocket costs. In November 2018, manufacturers announced an unprecedented 60% reduction in the price of PCSK9is. The effect of this price reduction on access and cost has not been previously studied. Hypothesis: Did the large reductions in PCSK9i prices improve coverage and lower out-of-pocket (OOP) costs for Medicare Part D beneficiaries? Methods: Medicare Part D Prescription Drug Plan Formulary, Pharmacy Network, and Pricing Information files (2018-2022) were used to evaluate coverage, 30-day OOP and total costs, and formulary restrictions before (2018Q1-2019Q1) and after (2019Q2-2023Q1) the PCSK9i price reduction. Costs were calculated in the coverage phase, not the deductible or coverage gaps. Paired t-tests were used to determine statistical significance with a two-sided alpha of 0.05. Results: We examined Part D plans in the first quarter of each year from 2018 to 2023 (3,127 to 4,543 plans per year, 79% Medicare Advantage plans). Nearly all plans covered at least 1 PCSK9i before and after the price reduction (97% vs 100% of plans). The price reduction was associated with significant reductions in 30-day total costs (from $1,075 to $585; difference = $489; 95% CI $484 - $494; p <0.001) and 30-day out-of-pocket costs ($306 to $75; difference = $231; 95% CI $228 - $233; p<0.001) (Figure 1). The proportion of plans requiring coinsurance as a proportion as opposed to a fixed copayment amount declined from 97% to 15% (p<0.001). Conclusions: The reduction in prices of PCSK9i was associated with significant declines in total Medicare costs and projected OOP costs for Medicare Part D beneficiaries. Nearly all Part D plans cover at least 1 PCSK9i. Future studies should examine the impact of this price reduction on adherence and cost-effectiveness of these therapies.