Interest in the use of simulation techniques in education in the medical fields has increased over the past several years because these methods can solve many training problems. Simulations provide practice in various aspects of care without harm or inconvenience to the actual patient. Five types of simulations have been identified that vary in their fidelity to real situations—written simulations, three-dimensional models, computer based patient management problems, multi-media approaches and simulated patients. Each of these approaches to simulation can be designed to teach or evaluate different aspects of patient care. Each presents unique instructional design problems and opportunities. As the technology for instruction improves there will be a continued increase in the use of simulations as a teaching device.