The food-allergy risk assessment for transgenic proteins expressed in crops is currently based on a weight-of-evidence approach that holistically considers multiple lines of evidence. This approach recognizes that no single test or property is known to distinguish allergens from nonallergens. The stability of a protein to digestion, as predicted by an in vitro simulated gastric fluid assay, currently is used as one element in the risk assessment process. A review of the literature on the use of the simulated gastric fluid assay to predict the allergenic status of proteins suggests that more extensive kinetic studies with well-characterized reference proteins are required before the predictive value of this assay can be adequately judged.