The uniaxial behavior of Nitinol in different forms and at different temperatures has been well documented in the literature. Mathematical models for the three dimensional behavior of this class of materials, covering superelasticity, plasticity and shape memory effects have been previously developed. Phenomenological models embedded in FEA analysis are part of common practice today in the development of devices made out of Nitinol. In-vivo loading of medical devices has cyclic characteristics. There have been some indications in the literature that cyclic loading of Nitinol modifies substantially its behavior. A consortium of several stent manufacturers, Safe Technology and Dassault Systèmes Simulia Corp., dedicated to the development of fatigue laws suitable for life prediction of Nitinol devices has conducted an extensive experimental study of the modifications in uniaxial behavior of both Nitinol wire and tubing due to cyclic loading. This study is presented elsewhere in this Conference. The Abaqus Nitinol material model has been extended to capture some of the phenomena observed and is described in this paper. Namely, a preload beyond 6% strain alters the transformation plateaus; if the cyclic load amplitude is large enough, permanent deformations (residual martensite) are observed; the lower plateau increases; and the upper plateau changes. The modifications to the upper plateau are very interesting in the sense that it appears broken: its start stress gets lowered creating a new plateau up to the highest level of cyclic strain, followed by resuming the original plateau until full transformation. A facility has been created in the software which monitors the preloading state, as well as the cyclic loading amplitude seen by each material point. Based on this data, the behavior of the material point is modified (or not) according to the experimental observations, and a final cyclic analysis is conducted. The model reproduces the experimental behavior quite well.