This study evaluated the USLE model in estimating water erosion in an Alfisol located in the town San Pedro, Chile's Me-tropolitan Region, with the use of erosivity values (R) obtained by approximating Arnoldus (IFM) and equations proposed by the Institute for the Conservation of Nature (ICONA) in Spain, adapted to the conditions of Chile. For the assessment of soil loss were used sediment data for each rainfall event during the period 1996-2000, measured in experimental plots tilled treatments, infiltration trenches and natural prairie. We compared the estimated erosion values with those measured on erosion plots in terms of basic statistics and indices based on difference and regression through the computerized system IRENE (Integrated Resources for Evaluating Numerical Estimates). In the descriptive and comparative analysis of the se-lected equations was determined that the estimated soil loss with the USLE equation using rainfall erosivity of ICONA, ob-tained with data from other locations, provided values that fit well with the values recorded in the study area, with slight variations. According to the results of the model was able to establish USLE approaches with respect to the tendency of the data, ie the estimated data were consistent and followed the same pattern from the data collected in the field.Revista Ciencia e Ingeniería. Vol. 36, No. 1, pp. 3-10, diciembre-marzo, 2015.CAZALAC, Chile