The United States produces approximately half of the world's soybeans. Although most of what is produced is used as animal feed, soy-protein products (eg, soy-protein flour, concentrates, and isolates) are used extensively by the food industry, primarily for their functional characteristics, such as emulsification. During the past decade, however, there has been a marked increase in the use of both traditional soyfoods, such as tofu and soymilk, and second-generation soyfoods, products which generally simulate familiar American dishes. Recently, attention has focused on the possible role of soybean consumption in reducing cancer risk. Soybeans contain, in relatively high concentrations, several compounds with demonstrated anticarcinogenic activity. Two of these compounds--protease inhibitors and phytic acid--have traditionally been viewed as antinutrients. The scientific community has begun to appreciate the potential importance of nonnutritive dietary compounds (phytochemicals) in foods such as soybeans. Dietitians need to become more aware of the phytochemical content of foods and the possible effect of phytochemicals on health and disease.