This paper presents a novel fully immersive Mixed Reality system that we have recently developed where the user freely walks in a life-size virtual scenario wearing an HMD and can see and use her/his own body when interacting with objects. This form of natural interaction is made possible in our system because the user's hands are real-time captured by means of a RGBD camera on the HMD. This allow the system to have in real-time a texturized geometric mesh of the hands and body (as seen from her/his own perspective) that can be rendered like any other polygonal model in the scene. Our hypothesis is that by presenting to the users an egocentric view of the virtual environment "populated" by their own bodies, a very strong feeling of presence is developed as well.