The widespread use of radiation sources in medicine, agriculture, industry, research and teaching, in spite of all the precautions taken, may cause accidents which result in injury or death of persons and damage to property. All practical steps to prevent such accidents must be taken and emergency actions planned in advance in order to limit injuries and damage. Emergency plans should be sufficiently broad to cover unforeseen or very improbable accidents as well as those that are considered more likely. Such plans should be established by the users of radioactive materials as well as by local emergency agencies and national competent authorities.