Evapotranspiration (ET) is one of the most important components of the hydrological cycle, but it is often the most difficult variable to determine at basin scale. Traditionally, ET is estimated using pointbased measurements collected at meteorological stations, but the non-spatial nature of these measurements often leads to significant errors when utilized at watershed scale. In this study, the METRIC (mapping evapotranspiration at high resolution with internalized calibration) approach was evaluated using remotely sensed observations from the moderate resolution imaging spectroradiometer sensor and data from meteorological stations in the lower catchment of the Buyuk Menderes Basin in western Turkey in the form of actual ET maps at daily and monthly intervals between 1st April and 30th September 2010. The energy fluxes and daily ET maps resulting from METRIC were compared with ET data estimated with the help of meteorological parameters. These results were found to be compatible with the ground-based estimations which suggest considerable potential for the METRIC model for estimating spatially distributed actual ET values with little ground-based weather data.