Systems providing routine food and nutrition surveillance (FNS) in local and national populations are essential to the understanding of relations between nutrition and health and the implementation of appropriate actions to promote the well-being of those populations. The purpose of an FNS program is to gather, interpret, and disseminate information about nutrition. Functions of FNS systems include national and regional planning, monitoring and evaluation of food and nutrition programs, provision of timely warnings of food shortages, problem identification, advocacy support, and monitoring food and nutrition effects of structural-adjustment policies. The characteristics of an FNS system are determined by its function. Successful FNS systems are community based and action oriented. We reviewed FNS systems throughout the world, with special emphasis on those in developing countries.