This retrospective cohort study of more than 1200 Medicare enrollees determined that adverse drug events (ADEs) increase the health care costs associated with such events. Building on a previous study in the same patient population, investigators measured costs in the 6 weeks before and immediately after a reported event. Based on the findings, they suggest that the annual costs related to ADEs for 1000 older ambulatory adults approaches $65,000, with more than a third associated with preventable events. The authors advocate for greater quality improvement efforts in this arena as the estimated cost savings make it an attractive and financially advantageous pursuit.