Aluminum, responsible of dialysis encephalopathy, is suspected to be involved in other neurological disorders such as Alzheimer disease. Absorption of aluminum from the digestive tract can be enhanced by the concommittant intake of substances such as citrate. We studied in rats and mice the interactions between fluoride and aluminum for their digestive absorption and showed that fluoride increased the levels of aluminum in plasma as much as citrate whereas aluminum decreased the absorption of fluoride. This result could be the consequence of the high affinity between aluminum and fluoride which form complexes able to increase the absorption of aluminum and to decrease the absorption of fluoride.