In the projects of anti-erosion protection in the Czech Republic, USLE was used as a standard tool for evaluating the risk of water erosion. The precision of the resulting USLE values is defined by the quality of input data and algorithms used. Two methods for LS factor calculation are recommended for use in the planning practice in the Czech Republic: the computing method based on the USLE 2D software and the other computing methods. Various methods can assess the LS factor; however, their results differ. On the example of the Starovice – Hustopeče study area (Czech Republic), strongly threatened by erosion, this report aimed to show the differences brought using these differing methods of LS factor assessment, all in two variants before and after application of anti-erosion measures (retention grass belts, grassed thalweg). Changes in the calculation of the LS factor were directly reflected in the calculation of the long-term average soil loss by water erosion.