In Morocco the concentration of fluoride in underground water in some phosphoric regions greatly exceeds the WHO standards. Defluoridation operations of brackish underground water have been carried out by two separation processes: adsorption on natural chitosan and electrodialysis using membranes CMX-ACS previously selected. The optimal operating conditions for fluoride removal by the chitosan have been determined firstly on synthetic water. Results indicate that both chemical adsorption on natural biopolymers and electrodialysis using specific, anion membranes demonstrated their capacity to remove fluoride from brackish water. The results show also that a coupling of these two processes is an interesting alternative to removal of fluoride for brackish water with a high fluoride content.