This study intends to continue the initial double-blind, placebo-controlled randomized clinical trial (NCT00318695) which involved 253 subjects with a first degree family history of allergic disease. The infants received at least 60ml of commercially available cow's milk based infant formula with or without probiotic supplementation (Bifidobacterium longum [BL999] 1×10*7 colony-forming unit (cfu)/g and Lactobacillus rhamnosus [LPR]2×10*7 cfu/g) daily from the first day of life for the first 6 months. A follow-up study (NCT00365469) up to 5 years of age is currently in process.