In this paper we present some results of surface soil moisture retrieval using data from ERS- 1/SAR collected in 1994. Concurrent to ERS-1/SAR overflights field data were collected over two subcatchments of the Zwalm catchment in Belgium. After presenting a data processing procedure we apply a theoretical backscattering model to the data set. By comparing the calculated backscattering coefficients to the observed ones, we conclude that the measurements of surface roughness parameters in current remote sensing campaigns are not accurate enough for retrieving soil moisture using theoretical backscattering models. A method based on simultaneous retrieval of surface roughness parameters and soil moisture using multiple ERS- 1/SAR measurements is hence proposed. Promising results on retrieved soil moisture confirm the validity of the proposed method.