In a prospective, randomized study, we have monitored the effect of maternal abstention from cow's milk and egg on the development of atopy in babies. Two hundred twelve women were followed from midpregnancy. We report the occurrences of allergies in their babies up to 18 months of age, as assessed by skin prick testing, determination of serum IgE, questionnaires, and blinded physical examination by a pediatric allergist. Whatever the method that was used, there was no statistically significant difference between babies whose mothers received the "diet" or the "nondiet." Other factors known to influence the risk of atopy like heredity, sex, month of birth, breast-feeding, and exposure to tobacco smoke, animal dandruff, and solid food did not differ between the groups. The mothers receiving the exclusion diet, by their own choice, had diminished their intake of milk and egg during lactation also, and therefore, their babies were significantly less exposed to cow's milk before 6 months. Still, atopy was equally abundant among their children. Thus, maternal elimination diet during late pregnancy did not protect the baby against allergy.