We have investigated the first stages of epitaxial growth of CdTe on ZnTe and ZnTe on CdTe with reflectance difference (RD) spectroscopy. Spectroscopic RD data show strong optical anisotropy responses at the critical points of the bulk dielectric function at the E-0, E-1 and E-1 + Delta(1) interband transitions of ZnTe and CdTe, respectively, which indicate that anisotropic in-plane strain occurs during epitaxial growth. Kinetic RD data taken at the E-1 transition of the respective material exhibit with an accuracy of 1 ML the onset of the formation of misfit dislocations for these material systems. (C) 2002 Elsevier Science B.V. All rights reserved.