This article reviews the literature describing four chemical and nuclear accidents and the lessons learned from each regarding the evacuation of civilian populations. Evacuation may save lives however, if poorly orchestrated, it may cause serious problems. For example, an inaccurate assessment of danger may lead to the evacuation of the same population twice, as the area requiring evacuation becomes larger than originally expected. Evacuation programs should focus on the vulnerable components of the populations, such as the elderly, children, and the disabled, and also should include plans for the care of pets and other animals. Training programs for civilians living near industrial centers and other high-risk areas should be considered. Finally, pre-event planning and preparation can improve the evacuation process and prevent panic behavior, and thus result in fewer casualties.