A cross sectional study using environmental and biological samples was undertaken to assess the association between arsenic (As) soil concentrations and urinary As levels of children living in an area where the soil is naturally As rich, during summer and winter. Twenty-nine children aged between 2 and 7 years from 21 dwellings in the summer study, and 23 of the 29 previous children from 17 dwellings in the winter study, were recruited. Housing characteristics, living conditions and individual characteristics were collected by questionnaire, and urine samples were collected for iAs+MMA+DMA measurement. Soil total As content and bioaccessibility were measured. Urinary As concentrations revealed that the children were not overexposed. Low bioaccessibility combined with moderately high levels in soil could explain this result. The concentration of arsenic in soil and soil-related factors appeared to contribute to the children's impregnation in summer but not in winter, which could be related to the children's behavior. This study highlights the need for additional studies of children to better understand their behavior, and obtain reference values in this particular population.Journal of Exposure Science and Environmental Epidemiology advance online publication, 18 July 2012; doi:10.1038/jes.2012.72.