Age-related morphological or functional changes are known to occur in numerous organ systems. In the case of the small bowel, only mild impairment of such functions as carbohydrate absorption and in particular vitamin D and calcium absorption have so far been reported. The latter is possibly of significance for the pathogenesis and treatment of osteoporosis. Other disturbances appear to have no clinical relevance, since the considerable functional reserve capacity of the small bowel can largely compensate them. To date, no morphological correlate has been established for the known functional disorders.