Introduction Numerous genetically engineered plant products have been extensively field tested and are moving towards market introduction. The first of these products, the FlavrSavr ? tomato, was recently introduced in the United States after lengthy consultations with the United States Food and Drug Administration. Confirming the safety and satisfying the appropriate regulatory agencies are key steps in the development of these products. A case study using soybeans that have been modified to be tolerant to glyphosate (glyphosatetolerant soybeans, GTS) will be used to illustrate the detailed technical assessment employed to establish that these soybeans are substantially equivalent to the soybeans in commerce today.We have carefully followed the guidance provided by both the Organization for Economic Cooperation and Development (OECD, 1993) and the Food and Drug Administration (US FDA, 1992) in assessing the safety of GTS. This assessment, which focused on the composition and nutrition of soybeans and the safety of the introduced protein that confers glyphosate tolerance, leads to the conclusion that GTS are substantially equivalent to the soybeans currently in commerce. Detailed compositional analysis of several other genetically engineered crops will be presented to verify that many of the genetically engineered crops being developed are substantially equivalent to the corresponding products currently marketed.