The article presents the results of 142 small mammal tissues biomonitoring at mining dumps of various ages at the locality of Lúky pod Tanádom (Banská Štiavnica, Central Slovak Neovolcanites). The investigation was realized in summer and in autumn to document the differences between the seasons. It was focused on livers, kidney and spleens of three dominant rodents: Apodemus flavicollis, Micotus arvalis and Clethrinomys glareolus. The contents of Fe, Mn, Cu, Zn, Pb, Cd and Bi were determined by atomic absorption flame spectrometry (AAS).