The elastic properties of Si/Ge strained-layer superlattices have been studied by means of Brillouin light scattering spectroscopy. The superstructures, grown along the [001] direction, have composition modulation wavelengths ranging from 1.4 to 5.6 nm and Si/Ge ratios: 1:1, 3:1, 4:1 and 1:4. The study has been carried out in three different stages: (i) the checking of the non-influence from the substrate on the determination of the elastic properties; (ii) the angular dependence of the surface sound velocity within the surface plane; and (iii) the variation of the surface sound velocity with the modulation wavelength. The obtained data of hypersonic surface waves are in good agreement with those calculated from previous results reported in Si and Ge pure single-crystals. No evidence of anomalous supermodulus effect has been found in these superlattices. (C) 1998 Elsevier Science S.A.