The Miocene deposits of the Carpathian Foredeep are relatively poorly recognized in geotechnical terms. The article analyzes the properties of the Krakowiec clays of the Przemyśl region, in particular physical and deformation parameters. In this part of the Carpathian Foredeep, clay usually occurs at considerable depth under younger Quaternary deposits. Particular attention was paid to the structural characterization of the tested samples. Structural heterogeneity of the studied clay, noticeable already at the stage of macroscopic studies, causes difficulties in conducting laboratory tests of strength parameters, especially the angle of internal friction and cohesion. The specific, layered, claysilt structure may cause difficulties in assessing load-bearing capacity and stability of the ground made of this type of soil. The unusual structure should draw attention of the contractors of geological-engineering and geotechnical documentation and encourage them to check mechanical properties by testing material with direct methods. An important issue is also forecasting changes in strain parameters in relation to the estimation of the effects of settlements of engineering structures.