The study covers 53 closed basins, the ones that their base are lagoons, located in the high plateau zones between the I and III region, in the North of Chile. The aim is to characterize the chemical aspects of the tributary waters; to make the hydric balance of the lagoons; and to set the hydrochemical evolution and the factors that control it. The dissolved compounds have a double origin, the volcanic rocks and the salts. The analysis of the evolution established two great groups.