Superelastic nickel-titanium (Ni-Ti), or nitinol, alloys are becoming integral to the design of a variety of new medical products. The enormous elasticity of these alloys is the most dramatic advantage afforded by this material, but by no means the only or most important one. Also discussed in this paper are features such as biocompatibility, kink resistance, constancy of stress, physiological compatibility, shape-memory deployment, dynamic interference, and fatigue resistance. Each of these properties is discussed and highlighted through examples of medical products including stents, filters, retrieval baskets, and surgical tools.