The U.S. Office of Alternative Medicine (OAM) of the United States National Institutes of Health held a 1985 conference to evaluate research needs in the field of complementary and alternative medicine (CAM). Its resulting guidelines have been used in this essay to describe three culture-based traditional healing systems and how they have interacted with allopathic biomedicine over the past several decades. After a brief description of Puerto Rican folk healing, it provides a first-hand observation of traditional Balinese shamanism and its encounter with Western psychiatry, the Andean Kallawaya system of healing and its interface with biomedicine, and Mexican-American Curanderismo and its long history of interaction with European medicine and, more recently, biomedicine in the United States. These systems are examples of ethnomedicine, a term that refers to the comparative study of medical systems in various cultures, focusing on beliefs and practices concerning sickness and health. It involves the observation and description of hygienic, preventive and healing practices, taking temporal and geographic references into account. From a post-modern perspective, it permits inspection of a dominant medical or healing system with those that lack equal power, and the outcomes of a clash between these systems.