An oft-cited belief that, until recently, simulators used in education of health care professionals were simple models is wrong. Hundreds of years ago and, in one instance, thousands of years ago, intricate models were used to help teach anatomy and physiology and in training in obstetrics and many surgical disciplines. Simulators were used to learn skills before performing them on patients and in high-stakes assessment.The newest technologies were often used in simulators to improve fidelity. In the 18th century, obstetric simulators could leak amniotic fluid, and blood were used to train midwives and obstetricians to recognize and manage complications of childbirth. Italy was the major source of simulators early in the 18th century, but in the 19th century, dominance in clinical simulation moved to France, Britain, and then Germany. In comparison, much of the 20th century was a "dark age" for simulation.