Inorganic arsenic has been classified as a human carcinogen (Group 1) by the International Agency for Research on Cancer. The Auvergne region has geological conditions conducive to the presence of arsenic in water. In 2001, more than 140,000 people were served by water systems with arsenic levels exceeding 10 μg/L (the quality standard in effect since 2003). The objective of this study was to investigate an association between the occurrence of certain cancers and chronic exposure to low-dose waterborne arsenic. This is an ecological correlation study conducted among the population residing in three departments of the Auvergne region. Exposure and health indicators were collected at the municipal level. The selected cancer sites were cutaneous melanoma, kidney cancer, bladder and urinary tract cancer, and lung cancer. A relationship between cancer incidence and exposure to arsenic in drinking water was investigated using a spatial analysis based on a Poisson regression model. The results highlight a significant association between the incidence of lung cancer in men and the presence of arsenic in water intended for human consumption. No association was observed in women for any of the cancers studied, nor in men for the other selected cancers. (R.A.)