Summary Among the components likely to be used in functional foods, prebiotics show interesting properties, and some are already recognised and used as food ingredients. A prebiotic has been defined as ’a non-digestible food ingredient that beneficially affects the host by selectively stimulating the growth and/or activity of one or a limited number of bacteria in the colon, and thus improves host health’. Inulin and oligofructose are the best-studied prebiotics so far. They are selectively fermented by the microflora in the human colon leading to a bacterial composition that is dominated by bifidobacteria, a perceived health-promoting genus. In this paper, the effects of these prebiotics, especially oligofructose-enriched inulin, on calcium absorption and bone metabolism are reviewed.