The clinical disadvantage of discarding old radiographs was evaluated in patients who had not been re-examined for more than 8 years after their last radiological examination, 38,772 in total. During the 1 year survey, 158 (0.41%) of them underwent re-examination after a long interval. Retrospective evaluation revealed that in only 12 patients (0.032%) were the old films useful. This survey suggested that the clinical risk of not referring to films more than 8 years old would be less than 0.049%. We consider this acceptable, and have formulated new guidelines of storage of films.