[en] The high concentration of uranium and thorium in certain Brazilian areas provides an opportunity to evaluate the radiation exposure due to intake of radionuclides by the populations that live and work in areas with a high natural radiation background. Buena, where this study was conducted, is a small village on the coast in the northern part of Rio de Janeiro State, characterised by the presence of a large deposit of monazite sand. In this paper, the concentrations of ²³⁸U, ²³⁴U, ²³²Th, ²²⁸Th, ²²⁸Ra, ²²⁶Ra and ²¹⁰Pb in faecal samples of inhabitants of this area was determined by a sequential analytical method. The results of the average concentration in faeces of inhabitants of Buena are 9.4 ± 3.4 mBq/g_ash for ²³⁸U, 9.2 ± 4.0 mBq/g_ash for ²³⁴U, 7.0 ± 4.2 mBq/g_ash for ²³²Th, 256.1 ± 134.6 mBq/g_ash for ²²⁸Th, 335.5 ± 192.8 mBq/g_ash for ²²⁸Ra, 156.6 ± 74.1 mBq/g_ash for ²²⁶Ra and 66.7 ± 17.7 mBq/g_ash for ²¹⁰Pb. The results were compared with the background concentrations from faecal samples from individuals living in Rio de Janeiro City. For most of the radionuclides analysed, the average concentration in faeces from inhabitants of the high natural radiation background were higher than the concentration found in Rio de Janeiro considered a 'normal' background area. (author)