Abstract
Health care organizations that deliver health care to a population are a major constituent of health care systems in many countries. Although some of the components of a health care organization may function as a simple or complicated system where interventions would yield the expected results, many parts of it function as complex systems within the organization. As such, is not always possible to predict changes or the effects of interventions on these systems due to their complex nature. Appreciation of the complex nature of health care systems and characteristics of these complex systems and their networks are necessary to manage health care organizations and changes in health care. This article described different types of systems and discusses why health care organizations are considered complex adaptive systems.