Fast x-ray fluorescence analysis with radioisotope excitation requires intense sources to produce reasonable counting rates. The inconvenience of handling such sources and the small number of suitable radioisotopes places severe limitations on their use. The possibility of using low-power x-ray tubes was explored using excitation sources for energy-dispersive fluorescence analyses. The principal advantage to x-ray tubes is the ability to produce x- ray fluxes to three orders of magnitude higher than those obtained with convenient radioisotope sources while dissipating only a few watts in the tube. As compared with normal radioisotope-target assemblies, excitation of a sample by the x-ray tube results in comparable sensitivity in only a tenth to one hundredth of the time.