We describe the method to extend the generalized Mie approach to the case of light scattering by uniformly anisotropic spherical particles by relating the wave packet representation and expansions for electromagnetic field over spherical harmonics. As a result, we define quasi-spherical modes in anisotropic medium. For radially anisotropic layer we determine the region of validity of Rayleigh-Gans approximation by comparing approximate values of the scattering cross-section with the results computed from the exact solution. We study the relative error for the scattering cross section as a function of the particle size, the anisotropy parameter and the layer thickness.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.