Among the interferometric modes and applications of RADARSAT-2 and RADARSAT-3, ScanSAR interferometry is interesting because of its wide swath imaging capabilities. It allows efficient mapping of the earth's surface topography and its changes, and poses several interesting requirements on instrumentation, data acquisition, and processing. These are discussed for RADARSAT-2 and RADARSAT-3. The signal properties of ScanSAR data are derived, and an interferometric ScanSAR product is proposed. A digital elevation model, derived from RADARSAT-1 ScanSAR data, is presented and demonstrates the feasibility of ScanSAR interferometry for topographic reconstruction.