Advances in the basic scientific research within the field of computer assisted oral and maxillofacial surgery have enabled us to introduce features of these techniques into routine clinical practice. In order to simulate complex surgery with the aid of a computer, the diagnostic image data and especially various imaging modalities including computer tomography (CT), magnetic resonance imaging (MRI) and Ultrasound (US) must be arranged in relation to each other, thus enabling a rapid switching between the various modalities as well as the viewing of superimposed images. Segmenting techniques for the reconstruction of three-dimensional representations of soft and hard tissues are required. We must develop ergonomic and user friendly interactive methods for the surgeon, thus allowing for a precise and fast entry of the planned surgical procedure in the planning and simulation phase. During the surgical phase, instrument navigation tools offer the surgeon interactive support through operation guidance and control of potential dangers. This feature is already available today and within this article we present a review of the development of this rapidly evolving technique. Future intraoperative assistance takes the form of such passive tools for the support of intraoperative orientation as well as so-called 'tracking systems' (semi-active systems) which accompany and support the surgeons' work. The final form are robots which execute specific steps completely autonomously. The techniques of virtual reality and computer assisted surgery are increasingly important in their medical applications. Many applications are still being developed or are still in the form of a prototype. It is already clear, however, that developments in this area will have a considerable effect on a surgeon's routine work.