High resolution, synoptic information on sediment characteristics of tidal flats is required for habitat mapping, and for assessing the distribution of benthic macrofauna. This study aims to derive information on surface characteristics of tidal flats from space-borne Synthetic Aperture Radar (SAR). Estimates of the backscatter coefficient were extracted from ERS-1 SAR and ERS-2 SAR PRI imagery of two tidal flats in the Westerschelde. They were related to field measurements of surface roughness, moisture conditions, sediment characteristics (median grain-size and silt content) and densities of benthic macrofauna. As predicted by the IEM backscattering model, a significant positive relationship was found between surface roughness and the backscatter coefficient: rougher surfaces were associated with higher backscatter values. In addition, median grain-size was positively correlated with backscatter, and silt content was negatively correlated with backscatter. Surface roughness was related to sediment characteristics: sandy sediment was found to be rougher than finer sediment, because surface ripples were more pronounced in the former. Significant relationships were also found between the sediment characteristics and macrofauna density. Relationships between sediment characteristics and backscatter were generally consistent in time. This demonstrates the potential of SAR for habitat mapping.