Abstract: This paper deals with the rendering issues of the problem of producing a real-time convincing surgery simulation. The main scope of our project is to simulate laparoscopic liver surgery. Nevertheless large parts of the technique apply to other organs. We address three aspects of the appearance of the organ surface: the organ skin texture, the specular highlights, and the reactions of the organ to the instruments. For this last aspect we address three effects: blood drops rolling on the surface, clear or deep cauterization, and whitening of the surface under local pressure. To meet the real-time constraint we use advanced graphics features such as multipass rendering, OpenGL texture extensions and lookup tables. Our target hardware are high-end graphics accelerators such as the SGI Infinite Reality. Nevertheless most of the techniques apply to low-end graphics accelerators.