Given that asthma results from a complex interaction between genetic susceptibility and environmental factors and rates of childhood asthma are increasing, primary prevention has to focus on modifiable aspects such as nutrition. There a implications from epidemiology that food supplementation with probiotics given to atopic mothers in pregnancy and during lactation can prevent the development allergies in the offspring. Children with atopic dermatitis are at increased risk (up to 80%) of developing persistent respiratory tract disease. Our trial examined whether probiotics are able to prevent allergic sensitization and allergic asthma when given to 6-24 month old infants at an increased risk of allergies.