Application of TiNi shape memory alloy in biomedical field is rapidly expanding. Some of the applications calls for non-conventional properties, which may require new methods of thermomechanical treatment and surface modification. In the present study, the effect of nanocrystallization/amorphization by various method of severe plastic deformation, such as, shot peening, cold rolling and high pressure torsion, was investigated on properties of TiNi shape memory alloys. Shot peening using iron based metallic glass media was found to be an effective method to obtain the amorphous surface. Surface amorphization improved the corrosion resistance. Nanocrystalline TiNi exhibited peculiar superelastic properties. Correlation between the microstructure and phase transformation in nanostructured TiNi was discussed.