The plastic deformation of a TiNi single crystal was modeled, taking into account the anisotropy of the yield stress in the slip plane. The material parameters (initial yield stress and hardening factor) were selected for each slip system. Deformation curves were obtained for different orientations of the single crystal. It is shown that Schmid's law prevents obtaining a correct description of deformation for all orientations of single crystals. Good agreement with experiments was observed for the crystal orientations 〈001〉, 〈111〉, and 〈123〉 but not 〈011〉, for which the deformation mechanism was different. In the case of the deformation of a polycrystalline sample, the anisotropy in the slip plane is not significant.