The author, faculty in a College of Medicine at a large Midwestern university, presented and discussed the use of a variety of simulation modalities in the instruction of medical students, residents, and medical clinicians. The author reported that at the time the article was written (1976) simulation technology had only been employed in limited areas of professional education. The article presented details on varying alternative simulation techniques for use in medical education or evaluation of learning and skills in medicine. This article provided a very good background on simulation models, modalities and specific uses of simulation as well as some advantages and limitations of simulation. The determination of validity on certain simulations was discussed and statistics presented. The author concluded that the evidence from studies of the use of simulation at several levels of medical education, with a variety of types of groups, suggested that when done properly, simulation exercises gave considerable promise of becoming a powerful tool for instruction and assessment of problem-solving skills.