One of the Food and Drug Administration's educational programs to optimize the use of medical radiation is the investigation of the efficacy of selected x-ray film examinations. The goal of this program is to provide clinical information needed to aid physicians in their judgment. The routine chest-radiograph screening examination has been studied, and recommendations for five applications of chest-radiograph screening have been published. These recommendations, plus results of FDA research on the efficacy of low-back radiography, are discussed.