Heterostructures of bulk-isotropic materials show optical anisotropies of various origins. The anisotropies reported so far can be categorized into four classes : surface-, interface-and confinement-induced anisotropies and bulk effects. Recent experimental results of ZnSe/GaAs (lattice matched but valence mismatched), GaN/GaAs (valence matched but lattice mismatched) and SiO2/Si (amorphous/crystalline) are reviewed in this article. The contribution from each class of the anisotropies to reflectance-difference (RD) spectra is examined using a simple optical model. These results demonstrate the capability of the RD technique to probe buried interfaces in situ in processing environments.