The hospital in the future will be faced with the major problem of managing and optimizing the use of images provided from numerous sources examining both anatomy (MRI, CT-scan...) and function (gamma-camera, PET-scan...). One of the first to benefit from such rationalization will be the surgeon. After studying the results of the physical examination, the laboratory reports and the medical imaging, the surgeon will decide on the best curative measured and the best surgical route before operating. He thus needs a computer to assist him in integrating the multi-modal information available for his patient, in particular the imaging with automatic integration and visualisation in synoptic mode (perception step), showing the trajectory of possible access routes to the target organ, memorization of the chosen route (decision step) and real operation either using laser or a manuel tool, or with robot assistance under human control (action step). This close cooperation between surgery and computers is called computer-assisted surgery. A few examples of current uses an future perspectives of this new field of surgery are presented.