Analysis of the rock-salt structures and of the conceptual model of SNF and radwaste repositories has shown that in the procedure of site selection, two types of host rocks namely, rock salt and salt-mudstones, should be considered. Laboratory investigations of the mineralogical, chemical, physical and geomechanical properties of salt-mudstones, from the point-of-view of their suitabilities for containing radwaste deposition, are described. The results obtained were compared with the results for rock salt. (C) 2003 Elsevier Science Ltd. All rights reserved.