The firsi aim of resistivitv survey is a study of any inhomogeneities. Frequently in practice the effect of anisotropy is displayed together with that of layenng or inhomogeneities. It coinplicates data mterpretation witlun the frainework of anisotropic models, and distorts resuits of interpretation in the framework of layered or inliomogeneous media. Ignoring of anisotropy resuits in wrong data interpretation. At the saine time anisotropy studying can give valuable geological information. That means that anisotropy itself and the mutual infinence of anisotropy and inhomogeneities needs to be studied. We have developed the efi'ective spectraJ algorithni for azimuthal resistivity survey (ARS) modeling over two-layercd (and multilayered) media witli the amsotropic basement. Its advantage is in the fact, that the most tabor-consuming part of the decision is carried Out in speetral domain, and then transformation of the decision info real doniain is fuifliled easily and fast for any azimuths. For two-layered model that approach gives the decision as series, when calculation goes fast and with controllable accuracy The spectral approach heips to fulliti more deep and full analysis of the decision. The ARS diagram is a periodic function, and has a discrete spectrum. With the help of ARS spectra the important fact was established: for any array above the anisotropic halfspace or horizontaily layered medium the odd harmonics are absent in the spectrum. These appear only when the current source is lowered on a depth or the array is placed near some inhomogeneities.The spectral approach has atlowed to explain many facts, established earlier for anisotropic media 1 2