Selenium (Se) concentrations were determined in human serum, rice and wheat flour sampled in the city of São Paulo, Brazil, and compared with those sampled in Tokyo. Japan. Serum levels of Se were significantly lower in Japanese Brazilians than Japanese living in Tokyo. The samples of rice consumed by Japanese Brazilians in São Paulo contained 22.7 ng Se/g on average, which was about half the selenium level in rice consumed in Tokyo. Rice commonly consumed in São Paulo might be one of the factors to lower the serum level of Se.