Small playa-lakes in Monegros, Spain, are high-value habitats for endemisms, threatened by landscape transformations and development of newly irrigated lands. The purpose of monitoring these fragile habitats is to detect their future disturbance, i.e. the effects of changing their natural hydrological regime, such as increasing their flooding surface area and habitat degradation by fresh and polluted water flow inputs. Landsat imagery is used for this purpose, facing the lack of regular ground data about their hydrological regime and the land covers with ecological meaning. Five meaningful thematic classes have been established grouping spectral classes obtained from unsupervised classification together with the visual interpretation of the original bands, the IHS transformation and the principal component analysis. The scarce ground data were confronted with the images. Compared to field work, remote sensing is advantageous for monitoring these playa-lakes, providing reliable insight to understand these habitats. Examples of how this research advances our knowledge about the nature and response of this ecosystem to adverse environmental changes are presented. Keywords: Wetland, Saline depression, Remote sensing, Endemism, Arid environment.