SummaryInfants born of allergic mothers but normal fathers, who had eczema and who were fed cows' milk, had a significantly greater incidence of asthma (P < 0.001) than infants with a similar history but who were breast‐fed. An analysis of all breast‐fed infants in the study showed that they were less likely to develop asthma than those who were bottle‐fed (P < 0.06).There was a lower incidence of allergy in infants born of families with allergic mothers and normal fathers, than in families in which both parents were allergic (P < 0.02).In skin tests of both breast or bottle‐fed babies, the two most common allergens eliciting reactions were egg and cat dander.