BACKGROUND: The prevalence of food allergy depends on the feeding practices of different parts of the world. Peanuts and nuts cause a great part of allergies in the United States; in Spain and Portugal are commonly due to fish, milk; in Italy seafood and mustard in France. In Mexico we don't know the frequency of food allergy and involved groups of age or specific foods. OBJECTIVE: To determine the frequency of immediate hypersensitivity for foods in allergic children from Hospital Infantil de México Federico Gómez. MATERIAL AND METHODS: A retrospective study was performed between January 1995 to December 1999. The skin prick test (SPT) to food was reviewed according to Aas classification. Male and female from 12 months to 18 years old were reviewed. RESULTS: We documented 1,419 patients with allergy. Of them 442 (31%) had positive skin prick test (SPT) to some of the 33 tested foods. The average age of the study group was of 12.8 years. The most affected was from 4 to 7 years (49%); the second group from 1 to 3 years with 23.7%, and the third was from 12 to 17 years with 13.5%. Fish, milky, seafood, soy, beans, orange, onion, tomato, chicken, nut, lettuce and strawberry, were responsible for 58% of the total of allergic reactions. Of those fish, milk, seafood, soy and orange (39%) had the highest frequency. Hypersensitivity to several foods is low, finding just one allergen in 50% of the cases, two allergens in 25%, three allergens in 9%, four in 7%, five in 5% and more than 6 only in 3% of cases. CONCLUSION: We concluded that almost any kind of food reaction seen in our study was due to alimentary habits of different populations, socioeconomic status, and availability of foods. This indicates the diversity of costumes in Mexican people due to the wide geographical area and cultural background of our country. Results could be increased because of only 33 allergens were tested.