High-resolution X-ray diffraction, X-ray reflectivity and X-ray diffuse scattering have been combined to characterize Si-Ge heterostructures. The discussion is focused on the complementary information content of the different X-ray scattering techniques in order to obtain a sample model that describes sufficiently all measured data sets. Quantitative information about composition, thickness, interface roughness and lateral correlation length was extracted from the measured data by fitting simulated curves. Unintentional compositional gradients could be detected and quantified. (C) 2003 Elsevier B.V. All rights reserved.