Young children sensitized with foods may develop early respiratory symptoms including nasal symptoms and cough, but not clinical manifestations in the skin or gastrointestinal tract. The long-term outcome of these patients is largely unknown. We studied 36 children sensitized with cow's milk and three different age-matched control groups. The patients were followed from 12 to 18 months of age for at least 5 yr with repeat skin testing and oral food challenge. After 2½ yr, 63.9% (n = 23) of those in the mild allergy group lost sensitivity to foods; after 5 yr, the number was 86.1% (n = 31). However, during the study period of 5 yr, 69.4% (n = 25) simultaneously developed a sensitivity to common indoor airborne allergens. A similar trend was found only in the egg allergy control group. A positive family history and a history of parental smoking significantly increased the relative risk (RR) of sustaining nasal allergy symptoms (RR = 3.33 and 1.79, respectively). We concluded that allergy march from food sensitivity to sensitivity to airborne allergens may occur in a subset of children before 4 yr of age. Genetics and environmental factors might independently contribute to the continuation of these respiratory symptoms.