Improving patient safety in hospitals is a longstanding national priority. Using longitudinal Medicare data from 2010 to 2019, this study identified a significant decrease in the rates of adverse events (e.g., adverse drug events, hospital-acquired infections, postoperative adverse events, hospital-acquired pressure ulcers, falls) over time among patients hospitalized for four common conditions – acute myocardial infarction, heart failure, pneumonia, and surgical procedures.