<p>Food allergy, which is a serious health problem in the world, can be controlled by avoidance of the causative allergens. For the purpose of avoidance of the allergen, it is essential to recognize the information of not only allergenic foods but also the allergens contained in the processed foods. In Japan, like several foreign countries, the duty to label the raw materials containing well known allergenic substances in the processed food will be bound in the year 2001. Previously, we reported an in vivo assay system on the basis of the mouse anaphylactic reaction using the abdominal wall (AW method). This system has widely been applicable to the detection of the food allergens. When the mice were sensitized with a purified protein allergen, the induction of the specific anaphylactic reaction by the allergenic protein contained in the processed food was attained comfortably, but it isn't always easy to obtain respective purified protein allergens for the foods to be tested. In order to normalize the practical detection of the protein allergen in the processed food, it is important to establish the conditions for the sensitization of mouse with not only the purified protein allergen but also the food itself containing the numerous ingredient. In the present paper, the screening tests of the allergenicity under the same condition [sensitization, FIA emulsion of 10 (W/V) % sample (50μL/mouse); challenge, 10 (W/V) % sample (50μL/site)] were performed and several cases with unclear results of estimation for allergenicity were studied further in detail. Foods known as the causes of food allergy, not only egg, milk, and soybean, but also peanut, chicken, oyster, calamary, kiwi, banana, and strawberry gave clear results in the usual screening for allergenic food tests. On the other hand, buckwheat, rice, wheat, shrimp, mackerel, codfish, and tomato did not show significant differences as compared to normal control group in the screening tests. For these foods, the screening conditions were modified as follows: (1) In the case of the poor sensitization; (a) improvement of the preparation method of the sensitizing solution (ultrafiltration treatment, elongation of the extraction time, or concentration of extraction, etc. of the food-extracted samples), (b) elongation of the sensitization term; (2) In the case of the valid sensitization; (a) removal of the contaminant in the challenging solution which causes a positive error in the challenging solution (elimination of the low molecule contaminant by the ultrafiltration or dialysis etc.), (b) improvement of the preparation method of the challenging solution (consideration of this modified conditions is similar to that described above (1-a)). The results of inducted anaphylactic reactions for the several allergenic foods by the most appropriate condition tested are shown in Table 1. Table 1. Induction of the Anaphylactic Reaction of several allergenic foods by AW (Abdominal Wall) Method [table]l</p>