We investigate the lattice dynamics of cubic CdS/ZnSe strained-layer superlattices grown on GaAs (001). Concerning the longitudinal vibrations our calculations based on a linear-chain model predict for this AB/CD-type superlattices confined optical and folded acoustic phonons as well as localized and extended interface modes. The calculated energies agree very well with the experimentally observed frequencies in Raman scattering experiments. BE using the bond polarizibilty model we discuss the relative scattering intensities of the different modes. The intensity of the localized Zn-S interface mode is of the order of the confined modes. The observation of this mode is supported by the behaviour of the overtone scattering of the longitudinal optical modes. (C) 3000 Elsevier Science B.V. All rights reserved.