The analysis of areas with different slope classes (A = 0-3%, B = 3-8%, C = 8-16% and D = 16-30%) is made with the purpose of verifying the TM/LANDSAT images potentiality in agricultural planning. Due to the absence of tridimensional viewing, the work is based on quantitative relations between drainage indices (river frequency and drainage density) determined on the images, and the relief expression (average slope) extracted from planialtimetric topographic charts (1: 50,000 scale). Aerial photographs on a 1:35,000 escale are utilized for comparisons. The main conclusion is that the utilization of TM/LANDSAT images in mapping slope classes through drainage network is feasible, though the characteristics of the analysed region caused an easier differentiation between areas of the A and B classes and those of the C and D classes.