Laparoscopic surgery has become an option for patients. However there have been some difficulties common to all laparoscopic procedures. Surgery simulation system for surgical planning and training is necessary and important in order to increase the safety of this surgery. We have been developing a surgery simulation system for laparoscopic assisted colorectal surgery utilizing patient-specific anatomy. In this system, we focused on the tissue deformation caused by laparoscopic right hemicolectomy manipulations, and applied a soft tissue model with anisotropic properties and a sphere-filled method. The sphere-filled model enables visualization of real-time deformations and is based on patient-specific data obtained from CT angiograms. The virtual laparoscopic instruments were emulated by manipulation of two PHANToM devices. As a result, the surgical maneuvers involved in laparoscopic colectomy, such as pushing and grasping of the mesentery and its vessels, were effectively simulated in real-time. In addition, surgeons are able to practice dissecting, isolating and dividing vessels with the virtual laparoscopic instruments.