The effect of azimuthal anisotropy on conventional P wave data is not a traditional subject for discussion in geophysical conventions. As a considerable number of 3D surveys, most of them involving a wide azimuth range, have been recorded and processed over a number of years, this situation is surprising: whenever accuracy and resolution are required, the effects of azimuthal anisotropy should be examined. To be realistic, the phenomenon is most often not very important, and it is not easy to produce evidence. As of now, one difficulty is in the very small size of the measurable effects, for example azimuth-dependent travel-time differences. More precisely, this size is most often below the level of uncertainty concerning velocity functions, especially in the presence of structures. It seems that real 3D tomography, which is not yet in use, would be the solution. However, in cases of very gentle and constant dip, detection is possible using simple investigations. In such cases, reservoir engineers will no doubt be interested in some of the attributes of azimuthal anisotropy, for example the orientation of the natural coordinates, and maybe some estimate of the intensity of the phenomenon.