Poor growth performance during infancy and early childhood is a frequent fact of life in most developing countries. Work in The Gambia has demonstrated that more than 43 % of observed growth faltering during the first 15 months of life can be explained by the presence of a mucosal enteropathy in the small intestine. Within communities the illness is very common: in the area investigated more than 95 % of infants above 8 months of age were affected, and on average they suffered a growth-limiting enteropathy for more than 75 % of their first year of life. Two mechanisms of weight loss have been defined. First, partial villus atrophy reduces absorption and digestion of lactose and probably other nutrients. Second, and more importantly, damage to the mucosal barrier allows translocation of macromolecules into the mucosa and blood, triggering both local and systemic immune and inflammatory mechanisms. Given the severity of the enteropathy it is not surprising that infants fail to grow at a normal rate. Recent findings suggest that these lesions continue throughout childhood and into adulthood. Thus, a persistence of chronic, local and systemic inflammation throughout childhood may be responsible for continued poor growth during this period. Although the nature of the enteropathy and the mechanisms of growth failure have been defined, the factors involved in the initiation and persistence of the intestinal lesion remain uncertain, making clinical management difficult. More work is clearly required to elucidate these factors and to define interventions to prevent or treat the enteropathy.