When a x-ray or gamma-ray beam strikes a film usually less than 1% of the energy is absorbed resulting in a photographic effect. Obviously, any mean of utilizing more fully the unabsorbed percentage of energy without complicating too much the technical radiographic procedure is highly desirable. One very common procedure is to use the film between two intensifying screens. These screens have the property of emitting electrons (lead screens) or become fluorescent (fluorescent screens) when stricken by electromagnetic radiation thus resulting in a supplementary photographic action on the film emulsion. This work presents an efficiency comparison of the more usual varieties of these intensifying screens for energies of x-ray until 300 K V. (author).