Most deformable models for surgery simulation are quite straightforward to achieve the computational speed required for real time simulation. However, they typically are more adjusted to merely graphical representation needs, i.e. surface-oriented (e.g. mass-spring type models), and neglect mechanical realism, although the simulation of cutting in real time is feasible. Finite element (FEM) based models, in turn, depart from continuum mechanics principles, and therefore are more realistic in many cases. But their volumetric structure is not optimal for graphical representation and in this sense produces excessive data, eventually impeding a real-time simulation of incisions. While parting from the same hypotheses as FEM models, a boundary element (BEM) based algorithm passes the influence of an organ.s interior to its surface. Thus, it yields comparable simulation results as the prior, but with less data to process. This enables the consideration in real time of local modifications of the underlying boundary element mesh produced when cutting. Actually, the presented algorithm has been successfully tested to simulate incisions in real time.