A large landslide occurred on the steep NW flank (Sciara del Fuoco) of the Stromboli volcano on December 30th 2002, following an intensification of the explosive activity of the volcano and the descent of a lava flow within the Sciara del Fuoco. Since February 20th 2003, this landslide is monitored through an innovative radar system installed on the flank of the Sciara del Fuoco. This apparatus, which was extensively tested by our research group for landslide monitoring, consists of a ground-based SAR (Synthetic Aperture Radar) interferometer, known as LiSA (Linear SAR), capable of producing a radar image of the observed area every 12 minutes, with a pixel resolution of about 2 m × 2 m. The interferometric analysis of sequences of consecutive images allows us to derive the entire deformation field of the observed portion of the Sciara del Fuoco and of the crater with a millimeter accuracy. The collected data are used for early-warning purposes, since they provide information over a wide area (about 2 km2), with a high accuracy and observation frequency. This note describes the results related to data acquired from February up to November 2003, which allow us to follow in detail the evolution of the slope instability of the Sciara.