The NNI knowledge series on Probiotics offers interesting articles on two aspects of probiotic use for paediatric health. The first article on “Probiotics and Immunity” reviews the role of probiotics in the development of the gut microbiota and the immune system. It also presents clinical data on the efficacy and benefits of probiotic supplementation, particularly in infants, pregnant and lactating women. The second article “Probiotics in Paediatrics: Functional, Safety and Regulatory Aspects” provides an outline on the safety aspect of probiotics in different populations, particularly infants and pregnant women. It also examines the regulatory framework that exists in India, USA and neighbouring countries.