A critical survey on the conditions of Nitinol surfaces modified using various modem techniques, oxidized in air / water / steam, and chemically / electrochemically passivated is presented. Various surface parameters are examined (elemental / oxide composition, organic / inorganic contaminants, crystalline vs amorphous character, heterogeneity, wettability) and their importance to the improvement of Nitinol corrosion resistance and biological performance is outlined. The impact of sterilization (ethylene oxide, plasma / H2O2 treatments, and various autoclaving protocols) on Nitinol surface is discussed. The presented analysis exemplifies a dual nature of the Nitinol surface reflecting the fact that we are dealing with a nearly equiatomic intermetallic compound. Varying such parameters as oxidation media, temperature, and electrical potential one can obtain either Ti - base surface with the only oxide TiO2, the most stable of titanium oxides beneficial for Nitinol biocompatibility or Ni - base surface built from less stable and easily soluble Ni oxides and hydroxides detrimental to Nitinol biocompatibility.