A paper by Gonzalez-Alonso et al . (1997) presents a regression estimator with excellent relative efficiency values to estimate the area of barley in an intensive agricultural area in Lleida (Catalonia, Spain) using 1994 ground survey data and a 1993 Landsat TM classified image. The paper concludes that the regression estimator can be efficiently applied with ground data from the current year and a classified satellite image from a previous year. If these conclusions are applicable to large areas, using the same classified image for several years would greatly increase the cost-efficiency of the regression estimator. This Letter evaluates the suitability of the method in other areas of Spain.