Chemical and mineralogical characteristics of three Psammic Soils occurring in the Lobo Creek Basin, situated at different topographic levels in Itirapina and Brotas municipalities were studied. The mineralogical homogeneity observed between horizons and profiles allows for the conclusion that these soils are derived from the same kind of parent material. The mineralogical maturity and the degree of roundness of the heavy residue indicate that these soils were subjected to the same intensity of transport. The chemical characteristics indicate that the soils present acid reaction and a distrophic and an alic character.