We are developing an ultrasonography training system that promises to accelerate the broader use of ultrasound imaging in healthcare. Aiming at cheaper, more efficient, and more effective ultrasound training, a key feature of our system is the real-time, interactive simulation of a 3D virtual patient that, unlike conventional, purely geometric models of the human body, includes deformable soft tissues. Since soft-tissue deformation is an important factor in the clinical practice of ultrasound imaging, our objective in this paper is to incorporate real-time interactive soft tissue mechanics simulation into our 3D patient model. To this end, we adapt and evaluate two well-known deformable model simulation methods-mass-spring-damper systems and the finite element method-and we apply these methods to the simulation of ultrasound imaging in soft tissues, obtaining promising results on a multicore laptop computer.