ABSTRACTA study in the Etueffont landfill, located in Belfort (France), was conducted to evaluate the performance of combiningnatural lagooning and use of two sand filters for treating leachates through the coupling estimation of several abiotic andbiotic parameters. Two gravel filters were installed in the upstream of the first basin which communicates with the remaing2, 3 and 4 basins. The distribution of physical-chemical (T, pH, Eh, EC, O2, SM, SO42-, Cl-, Zn, Fe, Mg, Ni, Al, As, Ba, Cu, Sn, Zn, BOD, COD, KN, NH4+, NO2- ,TP, AOX: absorbable organic halides, VFA: volatile fatty acids, and atrazine) and biological(bacteria, protozoa, phytoplankton) parameters was assessed in the leachate entering in basin 1, and downstream of thefilters. The results showed slight variations in the physical-chemical composition of the leachate between 1999 and 2000, most likely ascribed to the maturation of the landfill but a very significant removal of SM (suspended matter) by the sandfilters. This, applied to the majority of the studied parameters. Thus, the sand filter treatment of the leachates combined withnatural lagooning was efficient in the improvement of water clarification.