On May 16–17th, 2011, the First International Symposium on the Glycobiology of Human Milk Oligosaccharides was held at the Tivoli Hotel in Copenhagen, Denmark. The symposium was supported by Glycom A/S, Kongens Lyngby, Denmark. Human milk oligosaccharides (HMO)7 represent the third most predominant component in human milk but are absent from infant formula (1–3). Thus, oligosaccharide content represents the largest compositional gap between human milk and infant formula. Our understanding of HMO structure and natural variation in human milk has markedly expanded in the past decade, primarily due to advances in analytical methods (4, 5). HMO exert a number of important physiological functions, particularly in the early postpartum period, including facilitating the establishment of a healthy microbiota enriched bifidobacteria (6, 7), blocking the attachment of pathogens (8), and educating the neonatal immune system (9). Until now, direct study of dietary HMO function has been limited and commercialization has been blocked by lack of available material and high costs. Virtually no HMO were available from extractive sources and only a few synthesized in extremely low quantities and prohibitively high costs. However, due to the enormous biotechnological progress in HMO synthesis, the field is entering a new era focusing on specific biological effects of HMO in animals and humans.