Following an application from Specialised Nutrition Europe (formerly IDACE), submitted for authorisation of a health claim pursuant to Article 14 of Regulation (EC) No 1924/2006 via the Competent Authority of France, the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) was asked to deliver an opinion on the scientific substantiation of a health claim related to vitamin D and its contribution to the normal function of the immune system. The Panel considers that vitamin D is sufficiently characterised. A contribution to the normal function of the immune system is a beneficial physiological effect. The Panel has previously assessed claims on vitamin D and its contribution to the normal function of the immune system with favourable outcomes. The target populations were the general population and children aged 3 to 18 years. The Panel considers that the role of vitamin D in the functioning of the immune system applies to all ages, including infants and young children (from birth to three years of age). The Panel concludes that a cause and effect relationship has been established between the dietary intake of vitamin D and contribution to the normal function of the immune system. The following wording reflects the scientific evidence: ‘Vitamin D contributes to the normal function of the immune system.’ The target population is infants and young children up to three years of age.