The purpose of this study was to determine the content of oil, protein, lysine, and triptophan of 12 rice cultivars of the State of São Paulo. These data are of large interest as a support for the future rice breeding program in order to improve the nutritional value of this cereal. Significant differences were found for all the characteristics caused by vari-etal effects. Environmental factors, such as the year and the location where the rice grew, severely affected the protein content of all the cultivars, but for the IAC-47. In general, the low protein cultivars showed higher levels of lysine and triptophan. The IAC-47 cultivar revealed the most stable chemical composition and very promising to be used in the breeding for high-protein rices.