The application of human factors (HF) in improving medication-use safety is described. HF has been shown to improve the performance of people working within systems, especially in environments that rely on technology. HF applications in health care center around automation design and highly controlled environments, such as the operating room. To explore the application of HF to the highly variable process of medication use, an interactive conference was planned in which the fundamental principles of HF were presented to an audience of health care professionals. Workshops were organized to teach participants how to integrate HF into their practices, covering such areas as the basic principles of HF, applications of HF for improving medication-use safety, and strategic resources for organizations wishing to apply HF to their systems to improve medication-use safety. This report summarizes the highlights of this conference. By applying HF to existing and future systems, health care professionals can improve medication-use safety by reducing the occurrence of human errors. The culture, variability, complexity, and hierarchical nature of health care make the application of HF more difficult than in other environments in which some or all of these issues are less prevalent. Most health care providers are not educated in the discipline of HF, so it is important to increase their sensitivity to the limits of human performance and their understanding of the need to make system changes to accommodate these limits. Experts in this field can help health care professionals identify and improve complex, high-risk procedures and technologies. The potential benefit of hiring or consulting these experts requires organizations to make a commitment to change procedures, equipment, and their culture to improve patient safety.