Space borne differential synthetic aperture radar interferometry (DInSAR) has already proven its potential for mapping ground deformation phenomena, e.g. earthquakes, volcano dynamics, etc covering in continuity large areas. The innovative Persistent Scatterers Interferometry (PSI) technique, which overcomes several limitations of conventional SAR differential interferometry especially for applications in landslide studies, is suitable for monitoring slope deformations with millimetric precision. With PSI technique we detect the deformation, for long periods, that occur in an area as average annual deformation (mm/y) and is not spatially continuous but in terms of points (point targets). The aim of this study is to present preliminary results on the monitoring of slope instability in Panachaiko Mountain and particularly of the slopes facing the city of Patras. For this purpose we processed and analysed 42 ERS 1 and ERS 2 SAR scenes acquired in the time span 1992 and 2001, by applying the Interferometric Point Target Analysis algorithm. Point target reflectors with stable radar response over time were selected. In this case most of the point targets correspond to buildings of the local settlements or to rock outcrops. Additionally, millimetric target displacements along the line of sight direction were detected allowing measurements of slow terrain motion.