The current theory of Rayleigh and stochastic scattering in polycrystalline materials is reviewed and compared with (1) former theory and (2) experiment. Rayleigh scattering giving ultrasonic attenuation equal toSTf4(Sis the Rayleigh scattering factor,Tthe average scattering volume,fthe frequency) occurs when λ>2πD̄(λ is the wavelength,D̄the average grain diameter); stochastic scattering yielding ultrasonic attenuation equal to ΣD̄f2(Σ is the stochastic scattering factor) occurs when λ<2πD̄. The average scattering volume and average grain diameter must be evaluated by taking their averages over the grain‐size distribution in the metal. When this is done, the current theory accounts rather well for the scattering component of the ultrasonic attenuation in polycrystalline metals. Former theory underestimated the scattering. A tabulation is made of the scattering factorsSand Σ in various materials. The computed scattering factors show that polycrystalline samples of the following materials should have low attenuation: aluminum, chromite, chromium, magnesium, magnetite, silicon strontium nitrate, tungsten, vanadium, and YIG.