NiTi is only one of many alloy systems that exhibit the shape memory effect. The reason of his success is only the fact that it is the best in many aspects. His large market share created a significant price reduction so that in combination with its good properties, it became a preferential alloy even when compared with Cu-based alloys. Moreover NiTi alloys can be easily tuned to optimal performance by applying the proper combination of deformation and heat treatments. Its most successful applications are related to medical devices.