Shape memory effect (SME) is one of the smart features observed in some materials. SME, first discovered in binary alloys of Cu-Zn alloys and Cu-Sn alloys in 1938. It was not widely applied until the discovery of NiTi alloys in 1963. In addition to the shape memory effect giving the materials the ability to return to a predetermined shape when heated, NiTi shape memory alloys (SMAs) are capable of displaying pseudoelasticity giving the material the ability to transform between phases upon loading and unloading and recover to its original zero strain shape after significant deformation . With the properties such as repeatability, wear resistance, corrosion resistance and biocompatibility, NiTi is the most commercially successful shape memory alloy. <br />Nitinol ability to change shape as well as biocompatibility and hyper elasticity provide a great potential for its use in medical application. It has already been tested and implanted for a wide variety of treatments such as stents in cardiovascular surgery or for the esophagus in gastroenterology, as wires and brackets for orthodontics, in inter vertebral fusion (actipore), as well as for staples for foot surgery. The unique combination of properties of Nitinol offers exciting possibilities for the design of new devices and instrumentation. <br /><br />In the early 1960 s, Buehler and co-workers first explored the shape memory effect in an equiatomic NiTi alloy. This material, commonly referred to as "Nitinol", has been investigated extensively. Nitinol is an alloy of nickel and titanium in approximately 50:50 ratios. It is superelastic and can tolerate large strains without being irreversibly deformed. NiTi has two phases, called austenite and martensite. A decrease in temperature or applied stress induces the change of austenite into martensite. In the martensite form, the alloy can be largely strained and its macroscopic structure changed, when the specimen is heated or the load removed, the specimen returns to its original shape. This phenomenon is seen macroscopically as the shape memory effect. The shape memory and/or superelastic effect of NiTi alloys result from martensitic transformation taking place from a B2 to a B19̓ structure. Although its cost is still high, it is popular due to its strong SME behavior with transformation strains. The major physical properties of the basic binary NiTi system and some of the mechanical properties of the alloy in the annealed condition. NiTi can have two different forms; martensite or the low - temperature phase, and austenite or the high temperature phase. The main properties of the SMA are generally determined by the phase transition from austenite to martensite and vice versa. When the material is in its martensite from, it is soft and ductile and can easily deform. While austenitic NiTi is quite strong and hard (similar to titanium). <br />In recent years it became clear that the largest commercial successes of SMAs are linked to biomedical application. The combination of good biocompatibility, good strength and ductility with the specific functional properties such as shape memory effect and superelasticity creates a unique material for medical applications. Especially the superelastic effect of SMAs results in unique combination of high strength, high stiffness and high pliability; no other material or technology can offer this unique combination. <br /><br />