The Mesopotamia-Litoral region understand six Argentinean counties (Misiones, Entre Ríos, Corrientes, Formosa, Chaco and Santa Fe), with a total surface of 50 million hectares. This macro-region is part of the basin of the Plata River that includes the bordering countries; i.e. Uruguay, Brazil, Paraguay and Bolivia. The main rivers are the Paraná (medium and inferior), Paraguay and Uruguay, all of international character, besides numerous interior watercourses. This region has 18% of lands with cultivation capability (class I to III), 39% with grazing capability (class IV to VI), and a similar surface with extensive grazing capability (class VI-VII). Of the total, only 5% possesses highly cultivation capability (class I). Those lands are for the most part in the center-southern of the Santa Fe State. The occasionally arable lands (class V) and the non-arable lands cover 58% of the total area. These classes of land are in the north of Santa Fe (Salado river basin) and other counties (basin of the Superior Paraná, Medium Paraná and Paraguay). Chaco, Formosa and part of Entre Ríos have mainly lands with grazing capability, but they are arable. For this reason, these lands can sustain an important cattle production. In Argentina, a surface of 25 million hectares presents diverse degrees of soil erosion by water. The substitution of natural vegetation for crops, and the intensification of agricultural practices in landscapes with slopes greater than 1% and that receive annually more than 800 mm of rain were the main sources of the lands degradation. At the moment it is estimated that more than half of that surface (15 millions) are in the study Region. It is expected that the climatic change will produce changes in the intensity and magnitude of the precipitations, which in turn will increase the area with vulnerable lands to soil degradation. Since the available information for the studied region is heterogeneous and not up-to-date, the objective of this work was to elaborate maps of soil erosion by water - present and potential - starting from reliable information. The universal equation of soil loss (USLE) integrated to a geographical information system (GIS) was used. To estimate with securities the soil losses using these systems, one has to represent the USLE factors through mathematical functions or with measured values in a raster image. Based on the magnitude of the region, the working scale was 1: 250.000. The DEM was built starting from level curve maps that were digitized by the Military Geographical Institute (IGM). The potential soil erosion by water was established supposing bare soil (factors R, K and LS), while the present soil erosion was determined starting from the map of land use elaborated by the CIOMTA (2004). The land use distribution was: 23% agricultural use, 10% grazing, 59% natural vegetation (including areas with very low capability use), less than 2% of forest, and the remaining 7% is constituted by watercourses, lakes, and water reservoirs. The results indicate that lands of grazing-cultivation capability are over-used, especially in the counties of Missions and Entre Ríos. In these provinces, besides presenting higher slopes values, it is expected (in the next 80 years) an important increase in the intensities of rain, which severely increases the erosion hazards. This work allowed identifying areas of extreme vulnerability to soil degradation that in a short time should be switched to another kind of land use to protect them from accelerated soil erosion.