Some experimental facts concerning the anomalous diffraction pattern which arises when a laser beam o ray passes through a LiNbO3: Fe crystal with diffracted e ray and related phenomena in the Raman spectra are described. And the same method as was used in ref. 1 is applied to calculate the diffraction pattern quantitatively. Result of the calculations fits the experiment fairly well, this manifests the applicability of the theory of anisotropic diffraction of volume phase gratings to the anomalous diffraction with a 90° rotation of the polarization of the beams. Many other experimental facts are interpreted as well.