ABSTRACT:The anisotropy of sand has not been fully studied in terms of the effects of different silt content. This study investigates the effects on anisotropy in Tehran sand with various silt contents. The tests performed in this research include some Hollow Cylinder Torsion Shear Tests conducted on 400kPa confining stresses. The samples had 0, 15, 30, and 50 percent silt contents, and the effect of the inclination angle on the major principal stress "α" was investigated with a particular emphasis on silt content. The parameter "α" is considered as the key parameter that indicates the anisotropy characteristics, and can vary from 0 to 90 . According to the results, an increase of "α" leads to more contractive behaviours in the studied sands. In all samples, increasing the silt content up to 50% causes the strength to decrease.