[en] The presence of natural radioactive anomalies in rocks and soils of the state of Rio Grande do Norte may contribute to an increased exposure of the local population to natural radiation sources. From this region, there is a lack of information on the levels of natural radioactivity in drinking water supplies. Hence, this work focused on the characterization of the radiological and chemical aspects of the drinking water consumed in several municipalities of the Seridó Oriental region. Samples of surface water and groundwater were analysed for gross alpha and beta radioactivity and for the content of ²²⁶Ra. The most important physical and chemical parameters of the water are reported. Most of the monitored water parameter showed values higher than those recommended for a good organoleptic quality of the water. Gross alpha activity, ranging from <0.05 to 1.61 Bq/L, showed values higher than de permissible ones in two samples. Gross beta activity, corrected for ⁴⁰K contribution, ranged from 0.22 to 1.67 Bq/L. The activity concentration of ²²⁶Ra ranged from <0.01 to 0.53 Bq/L. Water quality can be considered poor, taking into the high levels of dissolved solids, affecting mainly the organoleptic characteristics of the water. Further investigation is needed to assess the behavior of the radiometric parameter in those samples with values higher than the permissible ones and to extent the study to other municipalities of the region. (author)