The Sorocaba River hydrographic basin locates in a sub-area known as Superior Medium Tietê in São Paulo State. The study was made in the low Sorocaba River. A relatively high diversity of fish species was noticed at that place, whose habits are also presumed to be diversified. The river in this region shows some important tributaries, which are the Sarapuí, Tatuí and Guarapó, and also a great number of smaller streams and marginal lagoons. Fishes were collected using gill-nets, purse seines, sieves and traps, line and hook, every month during two years. Fish species were 55, including 7 orders and 18 families. Characiformes and Siluriformes were the most represented with respectively 28 and 17 species.