There is growing interest in the potential for computer simulations to provide good training materials for abdominal endoscopic surgery. This talk describes a preliminary study of the mechanical properties of abdominal (spleen) tissue. Experimental force--displacement data can be used to derive a biomechanical model for the tissue as an incompressible, homogeneous, isotropic nonlinear elastic material with an exponential stress--strain law. The model can be used to predict the response of the tissue to a surgical probe, and there is a good fit between the computed solution and experimental data.