The ROBIOPSY project addresses the problem of the precise diagnosis of prostate cancer, and it aims at developing a method to guide the radiologist/urologist during the insertion of the biopsy needle towards the points of interest. The biopsy target will be identified by developing methods for the registration of MRI and US images, integrated with a simulation of the tissue deformation, so that the physician can precisely reach the prostate area identified in the MRI, but that may not be visible in the echographic images.