We prospectively studied the incidence of atopic disease in healthy term infants with a birth weight between -1 and -2 SD who were fed a cow milk formula during the first few days of life. A total of 216 infants were randomized to receive either early feeding with formula before normal breastfeeding was started (n = 112) or "normal feeding" with breastmilk (n = 104). Symptoms of allergy developed in 18% of the infants before 18 months of age in the formula fed group, as compared to 33% in the breastfed group (P less than 0.05). The difference was confined to the group of infants with a history of allergy in two family members. Thus, 11% of the formula-fed infants developed allergy symptoms, as compared to 61% of the control infants (P less than 0.01). Our study implies that early feeding during the first days of life with a cow milk formula, before the introduction of breastmilk, may reduce the incidence of allergy symptoms before 18 months of age in infants with a family history of allergy.