elastic scattering and inelastic scattering of conduction electrons by oscillating ionized impurities in semiconductors have been analyzed on the assumption that the scattering potential is the coulomb potential between the conduction electrons and the excess charge of the impurity ions and that the electrons are non-degenerate and have a simple spherical energy bands. two possible cases for impurity oscillations by thermal agitation are considered; (i) ionized impurities oscillating with a localized oscillating frequency [symbol] , widely separated from the normal acoustic and optical modes of the crystal, and (ii) ionized impurities oscillating with frequencies common to those of host lattice.