  The distance-dependence of the anisotropic atom-wall interaction is studied.
The central result is the 1/z^6 quadrupolar anisotropy decay in the retarded
Casimir-Polder regime. Analysis of the transition region between non-retarded
van der Waals regime (in 1/z^3) and Casimir-Polder regime shows that the
anisotropy cross-over occurs at very short distances from the surface, on the
order of 0.03 Lambda, where Lambda is the atom characteristic wavelength.
Possible experimental verifications of this distance dependence are discussed.
