Delayed introduction of allergenic foods has failed to prevent the development of food allergy in children. This observation has led to randomised controlled trials of early introduction of allergenic foods. These trials are presented in this review. Early introduction of peanut in the LEAP and EAT trials and the introduction of cooked egg in PETIT and EAT was safe and significantly reduced challenge-proven peanut and egg allergy. Further studies are needed to explore the optimal age for introduction to different allergenic foods to reduce the prevalence of food allergy.