On March 1979, a nuclear power station at Three-Mile Island (TMI) near Harrisburg, Pennsylvania, had a major breakdown. During the two-week period of the accident, about 150,000 residents were evacuated for reasons associated with safety and health. Many residents during and after the accident, regardless of whether they left or stayed, made mental and physical adjustments due to this accident. This paper is to estimate the economic costs incurred by individuals or communities as a result of a change in physical or mental health status and/or a change in health care services due to the TMI accident. The findings indicate that stress symptoms caused by the accident did affect the health-related behaviors of area residents. Of the costs examined, the economic costs of work days lost and physician visits are the largest cost items. There were some increases in consumption of alcohol, cigarettes, and tranquilizers immediately following the accident.