This study describes the influences of initial static shear stress (ISSS) and principal stress reversal on cyclic and post-cyclic deformation characteristics in triaxial compression and extension tests on medium-loose Toyoura sand. Results from post-cyclic monotonic triaxial tests on specimens with and without ISSS showed that that the post-cyclic stiffness of anisotropically consolidated specimens with an ISSS increased in compression, but decreased in the case of post-cyclic extension loading. On the other hand, the post-cyclic stiffness of specimens subjected to ISSS in the extension domain decreased during cyclic loading in compression and increased in extension.