The number of complementary and alternative medicines (CAMs) being utilized by North America health care consumers is growing at an astounding rate. There is a need by both health care providers and consumers to categorize CAM in order to make meaningful comparisons and informed decisions on their use. Four paradigms of health and illness are proposed that classify medicines according to the basic assumptions of health and disease associated with each medicine. CAMs classified in the body paradigm are those that work through biologic mechanisms, or in other words, target biologic factors as the primary determinants of health. The mind-body paradigm extends the body paradigm to include factors such as stress, psychologic coping styles, and social supports as primary determinants of health and disease. The body-energy paradigm assumes health and disease are functions of the flow and balances of life energies. The body-spirit paradigm assumes that one or more transcendental aspects or personalities existing outside the limitations of the material universe can influence health and disease. It is postulated that there is a hierarchical relation among the four paradigms, such that each paradigm essentially subsumes the assumptions of the previous ones, but adds additional assumptions that qualify the previous ones. Implications of this framework for clarifying many contemporary issues in health care are discussed.