In our university hospital, all of the radiographs have been stored since the hospital opening in 1974, and they can be retrieved easily. The total number of jackets is about 230,000. Access rates to them were surveyed, and it became clear that inactive jackets were increasing with the age of the hospital. On the contrary, fraction of active jackets increased slightly. Five radiologists evaluated the usefulness of referring to the previous films in the film reading processes. Subjects were 158 patients who were examined after the interval of 8 years or more. Assuming to discard their previous radiographs, the simple inaccessibility risk was 0.41% and the risk decreased to 0.0026% taking the clinical disadvantage into consideration. Risk to research works was estimated as 0.97%. Based on these surveys and evaluations, our university decided to discard radiographs of patients who had not revisited these 10 years with the exception of important cases for researches.