Food allergy was studied in a total of 866 Finnish children aged 1, 2, 3 and 6 years in the Helsinki region. The diagnosis was based on history as well as on elimination and challenge performed at home concerning fish, citrus fruit and eggs. The prevalence of food allergy was 19% at one year of age, increased to a peak of 27% at three years, and thereafter decreased to 8% at six years of age. The most common allergenic foods were citrus fruit, tomato, eggs, strawberry and fish. A positive history of food allergy could be confirmed by challenge in about half of the cases in the younger age groups and in 100% at six years of age. The data indicate that food allergy is common in Finnish children.