Augmented reality (AR) is a technology that expand the real environment by adding digital holograms into it. AR appears to be a promising field of development for serious games, especially for walking rehabilitation applications. The HoloLens device is one of the most popular and advanced AR Head Mounted Display (HMD). It includes optical and inertial sensors for position and orientation tracking. Although the algorithm combining the sensors information in the HoloLens can estimate the headset’s pose in an absolute reference frame, its reliability in walking condition is undocumented. Yet, the first step to develop high realistic application for gait rehabilitation, using position, velocity and acceleration of the headset, is to assess the reliability of the headset tracking, in comparison with a reference motion analysis tracking system, during different conditions. We hypothesis that the accuracy of the Hololens is sufficient to measure the position and the velocity of the headset, and the user by extension, without spatio-temporal drift.