Evaluation of thermo-mechanical properties of NiTi wires intended for vascular stent applications is carried out by combination of tensile tests at constant temperature with in-situ ultrasonic measurements (wave speed, attenuation) and electrical resistivity measurements. It is found that the mechanical and electric resistance results are mainly sensitive to R-B19’ stress induced martensitic transformation, but the ultrasonic wave speed and attenuation vary most significantly when the R-phase reorientation or distortion take place.