Possibilities and problems for the extraction of backscattering coefficients from airborne and spaceborne Synthetic Aperture Radar (SAR) data are discussed. Corrections for system errors and for imaging geometry are described. Examples are given for airborne SAR data acquired in theX- andC-bands over a test site in the Austrian Alps and for Seasat SAR data of glacierized areas in Iceland. From these data, backscattering coefficients have been derived on a relative scale for wet snow, glacier ice, and several ice-free surfaces. Data of in situ measurements on surface roughness and on dielectric parameters are presented for interpretation purposes and as the basis for backscatter modeling. The SAR-derived results are compared with theoretical backscattering calculations which were based on the Kirchhoff model for surface scattering and on the Born approximation for snow volume scattering.