Many plants have been genetically engineered to improve a specific property (e.g. delayed ripening and viral resistance) and are termed transgenic plants. Genetic engineering often results in the expression of one or more new proteins in the transgenic plant, and, although the amounts of protein produced are generally small, tests to check that these proteins do not cause allergies are required. In this study, procedures to test for the allergenic potential of food prepared from transgenic plants are discussed. Consideration is given to the source of the gene transferred into the plant (if the gene comes from an allergenic source then tests, such as radioallergosorbent tests, must be performed to check for allergenicity), comparison of physicochemical and biological properties (e.g. amino acid sequence and stability to digestion) of the new protein with those of known allergenic proteins and assessment of any allergens present in the plant prior to genetic engineering (to check that allergenicity does not alter in the transgenic plants).