This paper reports a study of three soil series occurring in the Taubaté basin, located at Rio Paraíba Valley, and it characterizes them from chemical, morphological and genetic points of view. The Ipiranga series develops in sandy-clay sediments of the tertiary period on slightly undulated topography. They are friable soils with a deep A horizon in relation to the B and the surface layers of coloration 10 YR become reddisher in depth (7.5 YR). They are acid and the have small contents of total and exchangeable bases. The SiO2/Al2O3 ratio in clay fraction is around 1.6. Kaolinite is the dominant clay mineral but one of mica structure is found at surface. It is possible that sediments from pre-Cambrian formation were settled in recent periods of time. The Coruja series occurs at a lower position where water influence is noted, although not being considered as of moderate drainage. Its origin is of sandy-clay sediments of tertiary period and of yellow color in its whole profile (10 YR). Its B horizon cannot be considered textural or colored, and the deep A horizon is remarkable. The soil is exhausted in exchangeable or total bases and its use in agriculture should depend on liming and fertilizers to improve the levels of plant nutrients. The clay fraction is domtnantly built up by kaolinite with small content of goethite and gibbsite. The Feital series follows the properties of the other two, having a deep A, and a colored B horizon. This series differs from the others on account of the depth, color and clay texture in the B. It is a porous, very acid soil and with low contents of exchangeable or total bases. In the clay fraction the most important clay mineral is kaolinite, with gibbsite, goethite and quartz (in a layer).