Motion-rendering enables the user to get haptic feedback of accelerations, produced by changing his position in the virtual world. Motion simulation systems, for decades mainly used for flight and drive simulation, represent an expanding tool for supporting this task. Due to the increasing use in theme-parks the systems became continuously more inexpensive, smaller, noiseless and easier to maintain. Nowadays the systems have features that make it possible to use them in typical virtual reality (VR) environments. This paper shows how VR can be completed by using motion-rendering. For that the paper gives an overall view of the basics of motion- rendering, different types of motion simulation systems and various possibilities to integrate a motion simulation system into a VR environment. Furthermore a prototypical motion-base- supported flight simulator, which is used for therapy of patients with fear of flight, is described.