Kostoľany area. The results of geochemical evaluation of soils in the studied region confirm high arsenic contamination of soils in the Nitra river catchement. The main contaminant in studied area is arsenic. The dominant value of which penetrated the environment by dam failure of ash from the combustion of brown coal with high arsenic content in the impoundment in Zemianske Kostoľany and its consecutive downstream warm-off to the surroundings in 1965. There were significantly higher total arsenic contents (AsTOT) on horizons which contain the ash (730-1264 mg. kg-1) in comparison with surface horizons, whereby both horizons have exceeded the hygienical levels for arsenic in soils. The higher As contents on the deeper horizons reflect the nature of old environmental burden, which include a dominant share of electricity ash containing arsenic bound for the actual mass of ash.