One manifestation of globalization is medical tourism. As its implications remain largely unknown, we reviewed claimed benefits and risks. Driven by high health-care costs, long waiting periods, or lack of access to new therapies in developed countries, most medical tourists (largely from the United States, Canada, and Western Europe) seek care in Asia and Latin America. Although individual patient risks may be offset by credentialing and sophistication in (some) destination country facilities, lack of benefits to poorer citizens in developing countries offering medical tourism remains a generic equity issue. Data collection, measures, and studies of medical tourism all need to be greatly improved if countries are to assess better both the magnitude and potential health implications of this trade.