Thanks to the availability of satellite data archives covering more than a decade, Permanent Scatterer SAR Interferometry (PSInSAR) nowadays represents one of the most powerful techniques capable of retrieving surface displacements of either natural (rock outcrops) or man made objects (buildings, infrastructures) already present within the surveyed area, acting as permanent radar reflectors. This paper describes the main features of PSInSARTM technique and the results of an application carried out on the Lake Sarez site.