Traditional medicine (a term used here to denote the indigenous health traditions of the world) and complementary and alternative medicine (T/CAM) have, in the past 10 years, claimed an increasing share of the public's awareness and the agenda of medical researchers. Studies have documented that about half the population of many industrialized countries now use T/CAM, and the proportion is as high as 80% in many developing countries. Most research has focused on clinical and experimental medicine (safety, efficacy, and mechanism of action) and regulatory issues, to the general neglect of public health dimensions. Public health research must consider social, cultural, political, and economic contexts to maximize the contribution of T/CAM to health care systems globally.