A study using137Cs, a component of radioactive fallout, was carried out to estimate soil erosion and deposition on a small watershed in Piracicaba District, São Paulo State, Southeastern Brazil. Soil samples were collected along three transects employing different land uses and conservation practices on different slopes.137Cs concentration was measured with a high-resolution germanium semiconductor detector coupled to a multi-channel analyzer. The137Cs estimates of soil movement and redistribution were related to slope, land use, and conservation practices, allowing the identification of sites with soil loss and accumulation. This study shows that the application of the137Cs technique is viable for Brazil. A relationship between137Cs concentration in soil profiles and soil losses or accumulations for Brazilian conditions needs to be established to avoid the use of equations developed for the Northern hemisphere.