The authors present the general data obtained, in the first phase of work, by the Soil Conservation Section of the Instituto Agronômico of the São Paulo Stale (Brazil), from the year 1943/44 to the year 1958/59. These data were obtained in experimental plots having runoff catching tanks installed at different times, totalizing 108 at the present, from which 38 at Pindorama, 29 at Campinas, 13 at Mococa, and 28 at Ribeirão Prêto. In the first part of this paper the original data obtained in each of the groups of experimental plots are presented as annual averages of soil and water losses, together with a brief description of the runoff tanks used and the general characteristics of the treatments in comparison. In the second part general average data for the main treatments and studied practices are presented, in an attempt to obtain a better representation of the general average conditions of the State of São Paulo. By this way were studied the effects on the erosion losses from the following factors, the treatments being rolled up in a decreasing sequence of soil losses: (I) Type of soil (sandy, clayish and «roxa»); (2) Soil tillage systems in corn crop (plowing twice with conventional moldboard plow, plowing once with conventional plow, and plowing once with subsurface plow ); (3) Organic matter incorporation in corn crops (burning the straw, velvet beans associated with corn turned under, green manure brought from outside, velvet beans associated with corn mulch left in the surface, and, manure); (4) Crop rotations (cotton, soybeans and corn); (5) Type of land use (cotton, coffee, pasture and woods); (6) Type of crop (castor beans, beans, cassava, peanuts, rice, cotton, soybeans, Irish potatoes, sugar cane, corn associated with beans, and, sweet potatoes); (7) Length of slope (100, 50 and 25 meters); (8) Some soil conservation practices in annual crops (down the slope planting, contour planting, alternated cultivation, and narrow strips of sugar cane).