Energy dispersion x-ray analysis using b, y, and x-ray emitting isotopes as the excitation source is an important extension of applied x-ray spectrography. Because of the low flux from the radioisotopic sources, x-ray resolution is achieved by physical or electronic discrimination as contrasted to bragg diffraction in conventional x-ray spectrography where the flux from the x-ray tube is 10 to the 6th power greater. Although the x-ray spectrograph employing wavelength dispersion is generally superior in the laboratory, there are many industrial control, mining, and environmental monitoring applications for energy dispersion systems. The compact low-cost units based on balanced filters for energy resolution are employed for a variety of single-element determination problems. High-resolution semiconductor detectors used with dedicated or time-sharing computers are becoming very important for rapid multielement analysis such as air pollution monitoring. Applications discussed include identification of scrap metals, measurement of coating thickness and composition, analysis of mining samples including in situ analyses down a drill hole, and determination of trace elements of environmental concern. For some of the trace element studies, radioisotopes are employed as the excitation source and as a collection monitor.