Background & Significance: Nurse burnout is a healthcare crisis affecting nearly half of U.S. hospital nurses and has been tied to negative patient outcomes such as preventable adverse events – the third leading cause of death in the U.S. Despite the pervasiveness of burnout, much remains to be understood about exactly how, and to what extent, hospital nurse burnout impacts the delivery of care and patient outcomes. This study advances our understanding of the complex phenomenon of burnout by examining its impact on specific nurse-reported preventable adverse events, and positing that missed care is a pathway by which hospital nurse burnout undermines quality of care and patient safety. Methods: This cross-sectional, secondary data analysis of three linked datasets from 2005-2008 assessed a sample of 23,784 registered nurses working in 587 hospitals across four states. Employing a series of multilevel multivariable robust logistic regressions, a mediation analysis was conducted to examine the associations between hospital-level nurse burnout, hospital-level missed care, and five nurse-reported frequent adverse events (medication errors, pressure ulcers, falls with injury, hospital-associated urinary tract infections and central line bloodstream infections), after controlling for patient severity, nurse and hospital characteristics. Results: Hospital nurse burnout was found to be significantly associated with all five nurse-reported adverse events and missed care partially mediated this relationship in four out of the five outcomes. The odds of nurses reporting frequent adverse events increase by 12-20% with every 10% increase in the proportion of burned out nurses, after accounting for patient severity, nurse and hospital characteristics. Missed care was found to explain 15-33% of the relationship between hospital nurse burnout and hospital nurse-reported adverse events. Conclusion & Implications: This study provides new evidence that hospitals with higher proportions of burned out nurses have higher odds of nurse-reported preventable adverse events—partially due to missed care. To the author’s knowledge, this is the first large-scale study in the U.S. to document these associations and empirically demonstrate that missed care partially explains how nurse burnout leads to preventable harm to patients. Given the current policy climate increasingly demanding safe, high quality, value-based patient care, this study suggests that organizational-level interventions aimed at reducing nurse burnout may be a critical strategy to mitigate costly, occasionally life-threatening adverse events.