This chapter explores efforts to enhance medical simulation for training with mixes of live, virtual, and constructive simulations. It reviews game-based training systems, virtual patients in virtual worlds, and partial task trainers. The chapter addresses the appropriate fidelity to meet the training requirements. It examines challenges, emerging technologies, and areas for research in medical training. One of the many design issues that affect both virtual patient and mannequin development is determining what level of fidelity is required to accomplish training. Mannequin-based patient simulators have been used to train tens of thousands of soldiers over the past several years, yet they have also been the source of significant controversy across the force. In 2004, the Simulation and Training Technology Center established the Advanced Medic Training Technologies US Army Technology Objective, with a mission to develop a wireless, field-capable medical simulator for training military medical skills from the point of injury to the hospital.