In recent years, lactose-free and low-lactose infant formulas have been increasingly used. The impact of using different carbohydrates than lactose on later cognition of formula-fed infants remains, however, unknown. We examined the effects of providing formulas containing either digestible maltodextrin or lactose as main carbohydrate source (28% of total nutrient composition) on cognitive performance of piglets. Piglets received the formulas from 1 to 9 weeks of age and, starting at 12 weeks, were individually tested in a spatial holeboard task (n = 8 pens/formula), in which they had to learn and memorize a configuration of baited buckets. After 28 acquisition trials, piglets were subjected to 16 reversal trials in which the location of the baited buckets was changed. Piglets fed the maltodextrin-based formula had higher reference memory (RM) scores than piglets fed the lactose-based formula towards the end of acquisition. During the switch of configuration, piglets offered the maltodextrin-based formula tended to have higher RM scores and make fewer RM errors than piglets offered the lactose-based formula. Working (short-term) memory was not affected by the formulas. Compared to lactose, the use of maltodextrin in milk formulas improved long-term spatial memory of piglets, even weeks after the end of the intervention. Lactose is the primary carbohydrate in human breast milk and milk-based formulas for infants 1. The specific need for lactose, however, has not been proven 2 and, in recent years, lactose-free or reduced-lactose formulas have been increasingly used 3. This increase in the use of infant formulas containing alternative carbohydrate sources is mainly driven by the increasing concern surrounding lactose intolerance in infants 4. In the European Union, some authorized glycaemic carbohydrates, like pre-cooked starch, gelatinized starch, and maltodextrin, are commonly used in infant and follow-on formulas as alternative sources of carbohydrates 5. Digestible maltodextrin is a low-sweet saccharide polymer consisting of D-glucose units primarily linked linearly with α-1,4 bonds; it also has a branched structure through α-1,6 bonds. Similar to lactose, maltodextrin has an approximate energy value of 4 kcal/g, and is the main carbohydrate source in non-allergenic infant formulas containing non-dairy ingredients 6. The use of maltodextrin as a source of digestible carbohydrates in infant formulas has been suggested to help reduce osmotic load and related intestinal distress 6 , while having no adverse effects on growth 7. Although maltodextrin is thus generally considered safe for infant development, little is known on the long-term consequences of replacing lactose with maltodextrin for health and biological functioning later in life. Early nutrition can influence development and may result in long-lasting adaptations of metabolic, immune, behavioural and brain functions in later life, a phenomenon known as nutritional programming 8-12. Carbohydrates, notably, are one of the primary sources of energy for the development and growth of infants,