Some adverse events are sensitive to aspects of nursing care, including pressure injuries, falls, hospital-acquired urinary tract infections, and medication administration errors. This retrospective study, based on patient discharge data from three Irish hospitals, characterized nursing-sensitive adverse events and associated costs. Results indicate that 16% of patients experienced at least one nurse-sensitive adverse event during their inpatient stay and that each additional nurse-sensitive adverse event was associated with a significant increase in length of stay. Extrapolated nationally, the authors estimate the economic burden of nurse-sensitive adverse events to the Irish health system to be €91.3 million annually.