Errors during administration are one of the most common types of medication errors, with one study showing that they occur in nearly 25% of doses in hospitalized patients. Lean methodology, derived from the Toyota Production System, is increasingly being used in health care as a way to design safer and more efficient systems of care. This study reports on the application of Lean approaches to improving medication administration safety. A redesigned medication administration system that incorporated human factors engineering techniques to minimize interruptions, implement barcode medication administration, and standardize nursing workflows resulted in a significant reduction in administration error rates. The study provides a useful example of how quality improvement techniques originally developed in other industries can be successfully applied in health care.