Many medical or surgical interventions can benefit from the use of computers. Through progress of technology and growing consciousness of the possibilities of real clinical improvements with computers, what was in the past the privilege of very few operations (mostly stereotactic neurosurgery) is now entering many surgical specialities. Although many technical issues remain to be solved, there is virtually no limit to the introduction of computers and robots in any surgical speciality. This tendency can take on the most varied forms. At the authors’ institute, three golden rules have guided the computer assisted medical interventions (CAMI) project for about ten years: 1) conceive systems for which the clinical value is well defined; 2) develop generic tools that can be applied to many different clinical applications; and 3) provide efficient collaboration between the surgeon and the system through simple interfaces