Plant biotechnology is beginning to result in new food products. Prior to introduction, transgenic plant varieties must be shown to be safe ecologically and safe to consume. An important consideration is an assessment of potential allergy to foods derived from transgenic plant varieties. The original source of the gene serves as a focal point - if a gene is obtained from an allergenic food source, it should be demonstrated that the gene does not encode an allergen. For non-allergenic gene sources, information should be obtained by comparing the genetic and physicochemical parameters of the encoded protein to common food allergens. The genes introduced into plants by genetic engineering were obtained from non-allergenic sources, do not encode allergens, and express proteins at very low levels. Significantly, the expressed proteins are extremely labile under simulated digestive conditions, whereas food allergens are resistant to digestion. Assessing a combination of these and additional factors provides assurance that transgenic plants will not increase the allergenicity of the food supply.